ifnotundef

A set of helper functions that simplify the (is a undefined ? b : c) syntax

Author: Loïc Formont
License: MIT Licensed
Example

var undef = require("ifnotundef");

• ifnotundef
  • .if(a, b, [c]) ⇒ *
  • .is(a, b) ⇒ boolean
  • .isnot(a, b) ⇒ boolean
  • .check(a, b) ⇒ boolean
  • .try(a, [b]) ⇒ *
  • .child(a, b, c, [d]) ⇒ *

undef.if(a, b, [c]) ⇒ *

Two parameters mode If a is undefined, return b else a Three parameters mode If a is undefined, return c else b

Kind: static method of ifnotundef
Returns: * - a, b or c depending on their undefined status

| Param | Type | Description | | --- | --- | --- | | a | * | the first parameter | | b | * | the second parameter | | [c] | * | the third parameter |

Example
Two ways to use if. Either with two parameters (a||b):

var myHost = undef.if(options.host, options.hostname);

or with three parameters (a?b:c):

var myHost = undef.if(options.host, options.hostname, 'localhost');

undef.is(a, b) ⇒ boolean

Invert of "check"

Kind: static method of ifnotundef
Returns: boolean - a or a[b]'s undefined status

| Param | Type | Description | | --- | --- | --- | | a | * | the variable to check | | b | * | the child path |

Example

if(undef.is(options.host)) console.log('Deal with it');

undef.isnot(a, b) ⇒ boolean

Alias of "check"

Kind: static method of ifnotundef
Returns: boolean - a or a[b]'s undefined status

| Param | Type | Description | | --- | --- | --- | | a | * | the variable to check | | b | * | the child path |

Example

if(undef.isnot(options.host)) console.log('Great');

undef.check(a, b) ⇒ boolean

One parameters mode If a is undefined, false else true Two parameters mode If a[b] is undefined, false else true

Kind: static method of ifnotundef
Returns: boolean - a or a[b]'s undefined status

| Param | Type | Description | | --- | --- | --- | | a | * | the variable to check | | b | * | the child path |

Example

if(!undef.check(options.host)) console.log('Deal with it');

undef.try(a, [b]) ⇒ *

One parameters mode If a is undefined, throw a else return a Two parameters mode If a is undefined, throw b else return a

Kind: static method of ifnotundef
Returns: * - a or exception depending on a's undefined status

| Param | Type | Description | | --- | --- | --- | | a | * | the parameter to try | | [b] | * | the error message |

Example
Two ways to use if. Either with one parameter:

var myHost = undef.try(options.host);

or with two parameters:

var myUndefined = undef.try(undefined, 'undefined is not defined ... ;-)');
// Exeption raised above

undef.child(a, b, c, [d]) ⇒ *

Three parameters mode If a[b] is undefined, return c else a[b] Four parameters mode If a[b] is undefined, return d else c

Kind: static method of ifnotundef
Returns: * - a[b] or c or d depending on their undefined status

| Param | Type | Description | | --- | --- | --- | | a | * | the object | | b | * | the child path | | c | * | the first value | | [d] | * | the second value |

Example
Two ways to use child. Either with three parameters (a[b]||c):

var myHost = undef.child(options, ['params', 'host'], 'localhost');

or with four parameters (a[b]?c:d):

var myHost = undef.child(options, ['params'], options.params.host, 'localhost');