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
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