xarg

A small tool for validating arguments in JavaScript

Install

npm install xarg --save

Usage

Every function will check if passed variable is defined and if it have a value of a specific type. This will throw an assertion error when values are not valid.

A list of available functions:

• isArguments()
• isArray()
• isArrayBuffer()
• isBoolean()
• isBuffer()
• isDate()
• isDefined()
• isEmpty()
• isError()
• isFinite()
• isFunction()
• isInteger()
• isMap()
• isNaN()
• isNil()
• isNull()
• isNumber()
• isObject()
• isPlainObject()
• isPromise()
• isRegExp()
• isSet()
• isString()
• isSymbol()
• isTypedArray()
• isWeakMap()
• isWeakSet()

To test your arguments you need to pass an object with data. For example:

xarg.isArray({a: [], b:[1,2,3], c: {}})

Examples

Example #1

function hello(text, age) {
  xarg.isString({text});
  xarg.isNumber({age});
}
  
hello('John', 25); // OK
hello([]); // AssertionError [ERR_ASSERTION]: "text" should be of type String, but got: object
hello('John'); // AssertionError [ERR_ASSERTION]: "age" should be defined
hello('John', 'abc'); // AssertionError [ERR_ASSERTION]: "age" should be of type Number, but got: string

Example #2

class APIService {
  constructor(url) {
    xarg.isString({url});
  }

  post(json) {
    xarg.isObject({json});
  }
}

const service = new APIService('https://example.com');
service.post({ data: '123' }); // OK

new APIService([]); // AssertionError [ERR_ASSERTION]: "url" should be of type String, but got: object
new APIService({}); // AssertionError [ERR_ASSERTION]: "url" should be of type String, but got: object

const service = new APIService(123); // AssertionError [ERR_ASSERTION]: "age" should be of type Number, but got: string
service.post('123'); // AssertionError [ERR_ASSERTION]: "json" should be of type Object, but got: string

Tests

Run tests:

npm test

Run tests with code coverage:

npm run test-cov