Underscore.js _.not() Method

The _.not() method returns a boolean value which is the opposite of the truthiness boolean value of the given value. 

Syntax:

_.not( value );

Parameters:

• value: Given value for returning opposite boolean.

Return Value: This method returns a Boolean value.

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: It returns false for this method.

Javascript

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

var bool = _.not( true );

console.log("Opposite boolean value if"
    + " value's truthiness is : ", bool);

Output:

Opposite boolean value if value's truthiness is :  false

Example 2: For false, this method returns opposite value that is true.

Javascript

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

var bool = _.not( false );

console.log("Opposite boolean value if"
    + " value's truthiness is : ", bool);

Output:

Opposite boolean value if value's truthiness is :  true

Example 3: For existing values, this method returns false.

Javascript

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

var bool = _.not( "Geeks" );

console.log("Opposite boolean value if"
    + " value's truthiness is : ",bool);

Output:

Opposite boolean value if value's truthiness is :  false

Example 4: for non-existing values, this method returns true.

Javascript

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

var bool = _.not( null );

console.log("Opposite boolean value if"
    + " value's truthiness is : ", bool);

Output:

Opposite boolean value if value's truthiness is :  true