Underscore.js _.exists() Method

The _.exists() Method checks whether the given value is “Existy” or not, correspondingly returning a boolean value. Both null and undefined are considered non-existy values. All other values are “Existy”.

Syntax:

_.exists( value );

Parameters:

• value: Given value to be checked for Existy value.

Return Value: This method returns a Boolean value(Returns true if the given value is Existy, else false).

Note: This will not work in normal JavaScript because it requires the underscore.js contrib library to be installed. 

underscore.js contrib library can be installed using npm install underscore-contrib –save.

Example 1:

Javascript

// Defining underscore contrib variable
var _ = require('underscore-contrib');

var bool = _.exists("Geeks");;

console.log("Given Value is Existy : ",bool);

Output:

Given Value is Existy : true

Example 2: For undefined, false is returned.

Javascript

// Defining underscore contrib variable
var _ = require('underscore-contrib');

var bool = _.exists(undefined);;

console.log("Given Value is Existy : ",bool);

Output:

Given Value is Existy : false

Example 3: For null also, false is returned.

Javascript

// Defining underscore contrib variable
var _ = require('underscore-contrib');

var bool = _.exists(null);;

console.log("Given Value is Existy : ", bool);

Output:

Given Value is Existy : false

Example 4:

Javascript

// Defining underscore contrib variable
var _ = require('underscore-contrib');

var bool = _.exists([1,12,2,3]);;

console.log("Given Value is Existy : ", bool);

Output:

Given Value is Existy : true