javascript-interface-library

various classification, validation and utility functions for JavaScript and TypeScript

From time to time, it's necessary to classify and/or validate the values of user inputs, data read from input streams (like files or network connections) or arguments passed as part of a function call. While TypeScript type annotations already eliminate the need for many of these tests, there still exist lots of interfaces to the outer (non-TypeScript) world where value checking remains important.

These situations are, what the javascript-interface-library has been made for.

NPM users: please consider the Github README for the latest description of this package (as updating the docs would otherwise always require a new NPM package version)

Just a small note: if you like this module and plan to use it, consider "starring" this repository (you will find the "Star" button on the top right of this page), so that I know which of my repositories to take most care of.

Installation

javascript-interface-library may be used as an ECMAScript module (ESM), a CommonJS or AMD module or from a global variable.

You may either install the package into your build environment using NPM with the command

npm install javascript-interface-library

or load the plain script file directly

<script src="https://unpkg.com/javascript-interface-library"></script>

Access

How to access the package depends on the type of module you prefer

• ESM (or Svelte): import { ValueIsListSatisfying, ValueIsOrdinal } from 'javascript-interface-library'
• CommonJS: const JIL = require('javascript-interface-library')
• AMD: require(['javascript-interface-library'], (JIL) => {...})

Alternatively, you may access the global variable JIL directly.

Note for ECMAScript module users: all module functions and values are exported individually, thus allowing your bundler to perform some "tree-shaking" in order to include actually used functions or values (together with their dependencies) only.

Usage within Svelte

For Svelte, it is recommended to import the package in a module context. From then on, its exports may be used as usual:

<script context="module">
  import { ValueIsListSatisfying, ValueIsOrdinal } from 'javascript-interface-library'
</script>

<script>
  console.log(ValueIsListSatisfying(
    [1,2,3,4], ValueIsOrdinal, 1,10
  ))
</script>

Usage as ECMAscript, CommonJS or AMD Module (or as a global Variable)

Let's assume that you already "required" or "imported" (or simply loaded) the module according to your local environment. In that case, you may use it as follows:

console.log(JIL.ValueIsListSatisfying(
  [1,2,3,4], JIL.ValueIsOrdinal, 1,10
))

API Reference

As shown above, the individual functions and values may either be accessed directly (when used as an ESM) or by prefixing them with their namespace JIL (in all other cases). The following documentation lists all module contents without namespace prefix only, and the shown function signatures are those used by TypeScript.

Object Functions

The JavaScript Object class provides a few useful functions (or "static methods") for inspecting or converting a given object. Unfortunately, these functions are often used without prior checking whether the given target object actually inherits from the Object protoype or was built using Object.create(null) - and will fail whenever such a "vanilla" object is given.

JIL therefore contains the following functions which mimic their counterparts from the Object class, but succeed even if the given target object is "vanilla".

• Object_hasOwnProperty (Value:Object, PropertyName:string):booleanreturns true if the given Value contains a property with the name PropertyName as its own property - or false otherwise. This function mimics the JavaScript method Object.hasOwnProperty
• Object_isPrototypeOf (Value:Object, Candidate:any):booleanreturns true if the given Value exists in the prototype chain of a given Candidate - or false otherwise. This function mimics the JavaScript method Object.isPrototypeOf
• Object_propertyIsEnumerable (Value:Object, PropertyName:string):booleanreturns true if the given Value contains a property with the name PropertyName as its own property and that one is enumerable - or false otherwise. This function mimics the JavaScript method Object.propertyIsEnumerable
• Object_toString (Value:Object):stringreturns a string which represents the given Value. This function mimics the JavaScript method Object.toString
• Object_toLocaleString (Value:Object):stringreturns a locale-specific string which represents the given Value. This function mimics the JavaScript method Object.toLocaleString
• Object_valueOf (Value:Object):anyreturns the primitive value of the given Value object. This function mimics the JavaScript method Object.valueOf

Value Classification Functions

The following functions check whether a given argument satisfies a certain constraint (e.g., belongs to a certain category) and return either true (if the constrain is met) or false otherwise.

• ValueExists (Value:any):booleanreturns true if the given Value exists, i.e., if it differs from both null and undefined - or false otherwise
• ValueIsMissing (Value:any):booleanreturns true if the given Value is either null or undefined - or false otherwise 
• ValueIsBoolean (Value:any):booleanreturns true if the given Value is either a primitive boolean value or an instance of Boolean - or false otherwise 
• ValueIsNumber (Value:any):booleanreturns true if the given Value is either a primitive numeric value or an instance of Number - or false otherwise
• ValueIsFiniteNumber (Value:any):booleanreturns true if the given Value is a finite number, i.e. a number which is not NaN and whose value is greater than negative and smaller than positive infinity - or false otherwise
• ValueIsNaN (Value:any):booleanreturns true if the given Value is NaN - or false otherwise
• ValueIsNumberInRange (Value:any, minValue?:number, maxValue?:number, withMin:boolean = true, withMax:boolean = true):booleanreturns true if the given Value is a number whose value is within the range given by minValue and maxValue - or false otherwise. minValue is optional and defaults to negative infinity, maxValue is also optional but defaults to positive infinity. When true, withMin indicates that Value may also be equal to the lower end of the given range, otherwise it must just be greater than the lower limit. When true, withMax indicates that Value may also be equal to the upper end of the given range, otherwise it must just be lower than the upper limit
• ValueIsInteger (Value:any):booleanreturns true if the given Value is a whole number - or false otherwise
• ValueIsIntegerInRange (Value:any, minValue?:number, maxValue?:number):booleanreturns true if the given Value is a whole number whose value is within the range given by minValue and maxValue - or false otherwise. minValue is optional and defaults to negative infinity, maxValue is also optional but defaults to positive infinity
• ValueIsOrdinal (Value:any):booleanreturns true if the given Value is a whole number greater than or equal to zero - or false otherwise
• ValueIsCardinal (Value:any):booleanreturns true if the given Value is a whole number greater than or equal to one - or false otherwise 
• ValueIsString (Value:any):booleanreturns true if the given Value is either a primitive literal value or an instance of String - or false otherwise
• ValueIsEmptyString (Value:any):booleanreturns true if the given Value is a string without any characters or with some content that consists of white-space characters only - or false otherwise
• ValueIsNonEmptyString (Value:any):booleanreturns true if the given Value is a string with some content that does not just consist of white-space characters - or false otherwise
• ValueIsStringMatching (Value:any, Pattern:RegExp):booleanreturns true if the given Value is a string whose content matches the given regular expression Pattern - or false otherwise
• ValueIsText (Value:any):booleanreturns true if the given Value is a string containing "ordinary" text only (i.e., a string which lacks any kind of control characters except \n or \r) - or false otherwise
• ValueIsTextline (Value:any):booleanreturns true if the given Value is a string containing a single line of "ordinary" text only (i.e., a string which lacks any kind of control characters) - or false otherwise 
• ValueIsFunction (Value:any):booleanreturns true if the given Value is a JavaScript function - or false otherwise
• ValueIsAnonymousFunction (Value:any):booleanreturns true if the given Value is an anonymous JavaScript function (i.e., a function without a name property) - or false otherwise
• ValueIsNamedFunction (Value:any):booleanreturns true if the given Value is a "named" JavaScript function (i.e., a function with a non-empty name property) - or false otherwise
• ValueIsNativeFunction (Value:any):booleanreturns true if the given Value is a native JavaScript function - or false otherwise
• ValueIsScriptedFunction (Value:any):booleanreturns true if the given Value is a scripted JavaScript function - or false otherwise 
• ValueIsObject (Value:any):booleanreturns true if the given Value is a JavaScript object (and not null) - or false otherwise
• ValueIsPlainObject (Value:any):booleanreturns true if the given Value is a JavaScript object (different from null) which directly inherits from Object (such as a Javascript object literal) - or false otherwise
• ValueIsVanillaObject (Value:any):booleanreturns true if the given Value is a JavaScript object which has been built using Object.create(null) - or false otherwise 
• ValueIsArray (Value:any):booleanreturns true if the given Value is an Array instance - or false otherwise. If given, minLength specifies the minimal required list length and maxLength specifies the maximal allowed list length
• ValueIsList (Value:any, minLength?:number, maxLength?:number):booleanreturns true if the given Value is a "dense" JavaScript array (i.e., an array whose indices 0...n-1 all exist, where n is the length of the given array) - or false otherwise
• ValueIsListSatisfying (Value:any, Validator:Function, minLength?:number, maxLength?:number):booleanreturns true if the given Value is a "dense" JavaScript array, whose elements all pass the given Validator - or false otherwise. Validator is a function which receives a list element as its sole argument and returns true if the given element is "valid" or false otherwise. If given, minLength specifies the minimal required list length and maxLength specifies the maximal allowed list length 
• ValueIsInstanceOf (Value:any, Constructor:Function):booleanreturns true if the given Value was constructed using the given Constructor function - or false otherwise
• ValueInheritsFrom (Value:any, Prototype:Object):booleanreturns true if Prototype exists in the prototype chain of the given Value - or false otherwise 
• ValueIsDate (Value:any):booleanreturns true if the given Value is a Date instance - or false otherwise
• ValueIsError (Value:any):booleanreturns true if the given Value is an Error instance - or false otherwise
• ValueIsPromise (Value:any):booleanreturns true if the given Value is a "Promise", i.e., an object with a property named then which contains a function - or false otherwise
• ValueIsRegExp (Value:any):booleanreturns true if the given Value is a RegExp instance - or false otherwise 
• ValueIsOneOf (Value:any, ValueList:any[]):booleanreturns true if the given Value equals (at least) one of the items found in the given ValueList - or false otherwise. Equality is checked using the JavaScript === operator 
• ValueIsColor (Value:any):booleanreturns true if the given Value is a string containing a syntactically valid CSS color specification - or false otherwise
• ValueIsEMailAddress (Value:any):booleanreturns true if the given Value is a string containing a syntactically valid EMail address - or false otherwise
• ValueIsURL (Value:any):booleanreturns true if the given Value is a string containing a syntactically valid URL - or false otherwise

Argument Validation Functions

The following functions check whether a given argument satisfies a certain constraint (e.g., belongs to a certain category) and either return the given argument (sometimes after some normalization), if the constrain is met, or throw an error otherwise.

Unless stated otherwise, these functions exist in four different "flavours", as indicated by their name prefixes:

• allowXXXvalidates the given argument and returns it, if it is either missing (i.e., equals null or undefined) or meets the condition defined for XXX - or throws an exception otherwise
• allwedXXXsynonym for allowXXX, looks better when used as an expression
• expectXXXvalidates the given argument and returns it, if it exists (i.e., differs both from null and undefined) and meets the condition defined for XXX - or throws an exception otherwise
• expectedXXXsynonym for expectXXX, looks better when used as an expression

For the sake of clarity, however, only the first "flavour" (namely allowXXX) is shown in the list below (provided that this flavour actually exists).

• expectValue (Description:string, Argument:any):anychecks if the given Argument exists (i.e., if it differs from both null and undefined). If this is the case, the function returns the given Argument, otherwise an error with the message "no ${Description} given" is thrown, which uses the given Description argument. Please note: this function does not exist in the flavours allowXXX or allowedXXX 
• allowBoolean (Description:string, Argument:any):boolean|null|undefinedchecks if the given Argument (if it exists) is either a primitive boolean value or an instance of Boolean. If this is the case (or Argument is missing), the function returns the primitive value of the given Argument, otherwise an error with the message "the given ${Description} is no valid boolean value" is thrown, which uses the given Description 
• allowNumber (Description:string, Argument:any):number|null|undefinedchecks if the given Argument (if it exists) is either a primitive numeric value or an instance of Number. If this is the case (or Argument is missing), the function returns the primitive value of the given Argument, otherwise an error with the message "the given ${Description} is no valid numeric value" is thrown, which uses the given Description
• allowFiniteNumber (Description:string, Argument:any):number|null|undefinedchecks if the given Argument (if it exists) is a finite number, i.e. a number which is not NaN and whose value is greater than negative and smaller than positive infinity. If this is the case (or Argument is missing), the function returns the primitive value of the given Argument, otherwise an error is thrown whose message contains the given Description
• allowNaN (Description:string, Argument:any):number|null|undefinedchecks if the given Argument (if it exists) is NaN. If this is the case (or Argument is missing), the function returns the primitive value of the given Argument, otherwise an error is thrown whose message contains the given Description
• allowNumberInRange (Description:string, Argument:any, minValue?:number, maxValue?:number, withMin?:boolean, withMax?:boolean):number|null|undefinedchecks if the given Argument (if it exists) is a number whose value is within the range given by minValue and maxValue. If this is the case (or Argument is missing), the function returns the primitive value of the given Argument, otherwise an error is thrown whose message contains the given Description. minValue is optional and defaults to negative infinity, maxValue is also optional but defaults to positive infinity. When true, withMin indicates that Value may also be equal to the lower end of the given range, otherwise it must just be greater than the lower limit. When true, withMax indicates that Value may also be equal to the upper end of the given range, otherwise it must just be lower than the upper limit
• allowInteger (Description:string, Argument:any):number|null|undefinedchecks if the given Argument (if it exists) is a whole number. If this is the case (or Argument is missing), the function returns the primitive value of the given Argument, otherwise an error is thrown whose message contains the given Description
• allowIntegerInRange (Description:string, Argument:any, minValue?:number, maxValue?:number):number|null|undefinedchecks if the given Argument (if it exists) is a whole number whose value is within the range given by minValue and maxValue. If this is the case (or Argument is missing), the function returns the primitive value of the given Argument, otherwise an error is thrown whose message contains the given Description. minValue is optional and defaults to negative infinity, maxValue is also optional but defaults to positive infinity
• allowOrdinal (Description:string, Argument:any):number|null|undefinedchecks if the given Argument (if it exists) is a whole number greater than or equal to zero. If this is the case (or Argument is missing), the function returns the primitive value of the given Argument, otherwise an error is thrown whose message contains the given Description
• allowCardinal (Description:string, Argument:any):number|null|undefinedchecks if the given Argument (if it exists) is a whole number greater than or equal to one. If this is the case (or Argument is missing), the function returns the primitive value of the given Argument, otherwise an error is thrown whose message contains the given Description 
• allowString (Description:string, Argument:any):string|null|undefinedchecks if the given Argument (if it exists) is either a primitive literal value or an instance of String. If this is the case (or Argument is missing), the function returns the primitive value of the given Argument, otherwise an error with the message "the given ${Description} is no valid literal string" is thrown, which uses the given Description
• allowNonEmptyString (Description:string, Argument:any):string|null|undefinedchecks if the given Argument (if it exists) is a string with some content that does not just consist of white-space characters. If this is the case (or Argument is missing), the function returns the primitive value of the given Argument, otherwise an error is thrown whose message contains the given Description
• allowStringMatching (Description:string, Argument:any, Pattern:RegExp):string|null|undefinedchecks if the given Argument (if it exists) is a string whose content matches the given regular expression Pattern. If this is the case (or Argument is missing), the function returns the primitive value of the given Argument, otherwise an error is thrown whose message contains the given Description
• allowText (Description:string, Argument:any):string|null|undefinedchecks if the given Argument (if it exists) is a string containing "ordinary" text only (i.e., a string which lacks any kind of control characters except \n or \r). If this is the case (or Argument is missing), the function returns the primitive value of the given Argument, otherwise an error is thrown whose message contains the given Description
• allowTextline (Description:string, Argument:any):string|null|undefinedchecks if the given Argument (if it exists) is a string containing a single line of "ordinary" text only (i.e., a string which lacks any kind of control characters). If this is the case (or Argument is missing), the function returns the primitive value of the given Argument, otherwise an error is thrown whose message contains the given Description 
• allowFunction (Description:string, Argument:any):Function|null|undefinedchecks if the given Argument (if it exists) is a JavaScript function. If this is the case (or Argument is missing), the function returns the given Argument, otherwise an error is thrown whose message contains the given Description
• allowAnonymousFunction (Description:string, Argument:any):Function|null|undefinedchecks if the given Argument (if it exists) is an anonymous JavaScript function (i.e., a function without a name property). If this is the case (or Argument is missing), the function returns the given Argument, otherwise an error is thrown whose message contains the given Description
• allowNamedFunction (Description:string, Argument:any):Function|null|undefinedchecks if the given Argument (if it exists) is a "named" JavaScript function (i.e., a function with a non-empty name property). If this is the case (or Argument is missing), the function returns the given Argument, otherwise an error is thrown whose message contains the given Description
• allowNativeFunction (Description:string, Argument:any):Function|null|undefinedchecks if the given Argument (if it exists) is a native JavaScript function. If this is the case (or Argument is missing), the function returns the given Argument, otherwise an error is thrown whose message contains the given Description
• allowScriptedFunction (Description:string, Argument:any):Function|null|undefinedchecks if the given Argument (if it exists) is a scripted JavaScript function. If this is the case (or Argument is missing), the function returns the given Argument, otherwise an error is thrown whose message contains the given Description 
• allowObject (Description:string, Argument:any):any|null|undefinedchecks if the given Argument (if it exists) is a JavaScript object (and not null). If this is the case (or Argument is missing), the function returns the given Argument, otherwise an error is thrown whose message contains the given Description
• allowPlainObject (Description:string, Argument:any):any|null|undefinedchecks if the given Argument (if it exists) is a JavaScript object (different from null) which directly inherits from Object (such as a Javascript object literal). If this is the case (or Argument is missing), the function returns the given Argument, otherwise an error is thrown whose message contains the given Description
• allowVanillaObject (Description:string, Argument:any):any|null|undefinedchecks if the given Argument (if it exists) is a JavaScript object which has been built using Object.create(null). If this is the case (or Argument is missing), the function returns the given Argument, otherwise an error is thrown whose message contains the given Description 
• allowArray (Description:string, Argument:any):any[]|null|undefinedchecks if the given Argument (if it exists) is an Array instance. If this is the case (or Argument is missing), the function returns the given Argument, otherwise an error is thrown whose message contains the given Description
• allowList (Description:string, Argument:any, Expectation?:string,minLength?:number, maxLength?:number):any[]|null|undefinedchecks if the given Argument (if it exists) is a "dense" JavaScript array (i.e., an array whose indices 0...n-1 all exist, where n is the length of the given array). If this is the case (or Argument is missing), the function returns the given Argument, otherwise an error is thrown whose message contains the given Description. If given, minLength specifies the minimal required list length and maxLength specifies the maximal allowed list length
• allowListSatisfying (Description:string, Argument:any, Validator:(Value:any) => boolean,Expectation?:string, minLength?:number, maxLength?:number):any[]|null|undefinedchecks if the given Argument (if it exists) is a "dense" JavaScript array, whose elements all pass the given Validator. If this is the case (or Argument is missing), the function returns the given Argument, otherwise an error is thrown whose message contains the given Description. Validator is a function which receives a list element as its sole argument and returns true if the given element is "valid" or false otherwise. If given, minLength specifies the minimal required list length and maxLength specifies the maximal allowed list length 
• allowInstanceOf (Description:string, Argument:any, constructor:Function, Expectation:string):any|null|undefinedchecks if the given Argument (if it exists) was constructed using the given Constructor function. If this is the case (or Argument is missing), the function returns the primitive value of the given Argument, otherwise an error is thrown whose message contains the given Description
• allowValueInheritingFrom (Description:string, Argument:any, prototype:any, Expectation:string):any|null|undefinedchecks if Prototype exists in the prototype chain of the given Argument (if that exists). If this is the case (or Argument is missing), the function returns the primitive value of the given Argument, otherwise an error is thrown whose message contains the given Description 
• allowDate (Description:string, Argument:any):Date|null|undefinedchecks if the given Argument (if it exists) is a Date instance. If this is the case (or Argument is missing), the function returns the given Argument, otherwise an error is thrown whose message contains the given Description
• allowError (Description:string, Argument:any):Error|null|undefinedchecks if the given Argument (if it exists) is an Error instance. If this is the case (or Argument is missing), the function returns the given Argument, otherwise an error is thrown whose message contains the given Description
• allowPromise (Description:string, Argument:any):any|null|undefinedchecks if the given Argument (if it exists) is a "Promise", i.e., an object with a property named then which contains a function. If this is the case (or Argument is missing), the function returns the given Argument, otherwise an error is thrown whose message contains the given Description
• allowRegExp (Description:string, Argument:any):RegExp|null|undefinedchecks if the given Argument (if it exists) is a RegExp instance. If this is the case (or Argument is missing), the function returns the given Argument, otherwise an error is thrown whose message contains the given Description 
• allowOneOf (Description:string, Argument:any, ValueList:any[]):any|null|undefinedchecks if the given Argument (if it exists) equals (at least) one of the items found in the given ValueList. If this is the case (or Argument is missing), the function returns the given Argument, otherwise an error is thrown whose message contains the given Description. Equality is checked using the JavaScript === operator 
• allowColor (Description:string, Argument:any):string|null|undefinedchecks if the given Argument (if it exists) is a string containing a syntactically valid CSS color specification. If this is the case (or Argument is missing), the function returns the primitive value of the given Argument, otherwise an error is thrown whose message contains the given Description
• allowEMailAddress (Description:string, Argument:any):string|null|undefinedchecks if the given Argument (if it exists) is a string containing a syntactically valid EMail address. If this is the case (or Argument is missing), the function returns the primitive value of the given Argument, otherwise an error is thrown whose message contains the given Description
• allowURL (Description:string, Argument:any):string|null|undefinedchecks if the given Argument (if it exists) is a string containing a syntactically valid URL. If this is the case (or Argument is missing), the function returns the primitive value of the given Argument, otherwise an error is thrown whose message contains the given Description

Utility Functions

• throwableError (Message:string):Errorthis function has been provided in order to simplify the construction of "named" Error instances: if the given Message starts with a JavaScript identifier followed by a colon, identifier and colon are stripped apart and the identifier is used as the name property of a newly constructed Error instance for the remaining part of Message. Otherwise, this function is equivalent to new Error(Message)
• throwError (Message:string):neverthis function has been provided in order to simplify throwing "named" Error instances: if the given Message starts with a JavaScript identifier followed by a colon, identifier and colon are stripped apart and the identifier is used as the name property of a newly constructed Error instance for the remaining part of Message. Otherwise, this function is equivalent to throw new Error(Message)  
• ObjectMergedWith (TargetObject:object, ...otherObjectList:object[]):objectObject.assign can not be used to copy properties with getters and setters from one object into another - this is what ObjectMergedWith is good for: it copies the descriptors of all own properties from any object found in otherObjectList into the given TargetObject and also returns that object as its function result. Any descriptor already existing for a given property in TargetObject will be overwritten 
• constrained (Value:number, Minimum:number = -Infinity, Maximum:number = Infinity):numberlimits the given Value to the range specified by Minimum and Maximum - i.e., the function returns Minimum if Value is less than (or equal to) Minimum, Maximum if Value is greater than (or equal to) Maximum, or Value itself otherwise. Minimum and Maximum are optional and default to -Infinity or +Infinity, resp. 
• escaped (Text:string):stringreturns a copy of the given Text in which all control characters have been replaced by their corresponding escape sequences
• unescaped (Text:string):stringreturns a copy of the given Text in which all character escape sequences have been replaced by their corresponding (control) characters 
• quotable (Text:string, Quote:'"' | "'" = '"'):stringreturns a copy of the given Text in which all control characters and Quotes have been replaced by their corresponding escape sequences. The outcome of this function may, f.e., used to construct literal values in JSON files. Quote is optional and defaults to the double-quotes character
• quoted (Text:string, Quote:'"' | "'" = '"'):stringreturns a copy of the given Text (embedded within a pair of Quotes) in which all control characters and Quotes have been replaced by their corresponding escape sequences. The outcome of this function may, f.e., used to construct literal values in JSON files. Quote is optional and defaults to the double-quotes character 
• HTMLsafe (Argument:string, EOLReplacement?:string):stringreturns a copy of the given Argument in which all control characters (except \n) and characters with a special meaning for HTML have been replaced by their corresponding HTML entities. Any linefeed characters (\n) will be replaced by the given EOLReplacement string - specification of EOLReplacement is optional and defaults to <br/>
• MarkDownSafe (Argument:string, EOLReplacement?:string):stringreturns a copy of the given Argument in which all control characters (except \n) and characters with a special meaning for (HTML and) Markdown have been replaced by their corresponding HTML entities. Any linefeed characters (\n) will be replaced by the given EOLReplacement string - specification of EOLReplacement is optional and defaults to <br/> 
• ValuesDiffer (thisValue:any, otherValue:any, Mode?:'by-value'|'by-reference'|undefined):booleanreturns true if thisValue differs from otherValue - or false otherwise. Equality is checked by inspection, i.e., null, undefined, booleans, strings and functions are checked using the JavaScript === operator, comparison of numbers also takes care of NaN and a potential deviation by Number.EPSILON and objects or arrays are (by default) compared element by element. If the optional Mode is set to by-reference, Objects are always compared by reference, if set to by-value, instances of Boolean, Number and String are always compared by their primitive value
• ValuesAreEqual (thisValue:any, otherValue:any, Mode?:'by-value'|'by-reference'|undefined):booleanreturns true if thisValue equals to otherValue - or false otherwise. Equality is checked by inspection, i.e., null, undefined, booleans, strings and functions are checked using the JavaScript === operator, comparison of numbers also takes care of NaN and a potential deviation by Number.EPSILON and objects or arrays are (by default) compared element by element. If the optional Mode is set to by-reference, Objects are always compared by reference, if set to by-value, instances of Boolean, Number and String are always compared by their primitive value 
• ObjectIsEmpty (Candidate:any):booleanreturns true if the given Candidate is an empty object (i.e., an object without any own properties) - or false otherwise
• ObjectIsNotEmpty (Candidate:any):booleanreturns true if the given Candidate is a non-empty empty object (i.e., an object with at least one own property) - or false otherwise
• StringIsEmpty (Candidate:string):booleanreturns true if the given Candidate is an empty string (i.e., a string which either contains no characters at all or only whitespace characters) - or false otherwise
• StringIsNotEmpty (Candidate:string):booleanreturns true if the given Candidate is a non-empty string (i.e., a string which contains one or more characters and not all of them are whitespace characters) - or false otherwise 
• ValidatorForClassifier (Classifier:(Value:any) => boolean, NilIsAcceptable:boolean, Expectation:string):Functionthis function is used internally to construct many of the offered argument validation functions: it returns a new function which takes a Description and an Argument, uses the given Classifier to check if Argument belongs to the expected category of values and - if it does - returns the primitive value of the given Argument. Otherwise, an error message is constructed, which includes the given Description and complains about the given value not being a "valid ${Expectation}" - i.e., Expectation should describe the expected kind of argument. If set to true, NilIsAcceptable indicates that Argument may be missing (i.e., null or undefined), otherwise the given Argument is mandatory. Important Note: if you plan to develop a library which may be "tree-shaked" by application bundlers (such as WebPack and Rollup) and export functions built with ValidatorForClassifier, you should mark all invocations of ValidatorForClassifier as "free of side-effects" by prepending them with /*#__PURE__*/ - otherwise those invocations will remain in the bundled code even if you don't use the corresponding exports
• validatedArgument (Description:string, Argument:any, ValueIsValid:(Value:any) => boolean,NilIsAcceptable:boolean, Expectation:string):any|null|undefinedthis function is used internally to actually validate a given Argument and throw an Error with a message containing the given Description, if not. ValueIsValid is the function used check Argument and should return true if Argument is "valid" or false if not. If set to true, NilIsAcceptable indicates that Argument may be missing (i.e., null or undefined), otherwise the given Argument is mandatory. If validation fails, an error message is constructed, which includes the given Description and complains about the given value not being a "valid ${Expectation}" - i.e., Expectation should describe the expected kind of argument 
• FunctionWithName (originalFunction:Function, desiredName:string|String):Functionthis function is used internally to convert an anonymous function originalFunction into a named one - either by setting the desiredName for the existing function or by wrapping it into a new function with that name

Color Utilities

• ColorSetis an object, whose keys are the names of all colors known by (and built into) a web browser and the corresponding values are the RGBA specifications of these colors
• HexColor (Color:string):stringconverts a given Color string (which must be a valid CSS color specification) into the long hexadecimal format (#rrggbbaa)
• shortHexColor (Color:string):stringconverts a given Color string (which must be a valid CSS color specification) into the short hexadecimal format (#rrggbb) - such a format must be used for HTML input elements of type "color"
• RGBAColor (Color:string):stringconverts a given Color string (which must be a valid CSS color specification) into the RGBA format (rgba(r,g,b,a))

Build Instructions

You may easily build this package yourself.

Just install NPM according to the instructions for your platform and follow these steps:

1. either clone this repository using git or download a ZIP archive with its contents to your disk and unpack it there
2. open a shell and navigate to the root directory of this repository
3. run npm install in order to install the complete build environment
4. execute npm run build to create a new build

If you made some changes to the source code, you may also try

npm run agadoo

in order to check if the result is still tree-shakable.

You may also look into the author's build-configuration-study for a general description of his build environment.

License

MIT License