Lodash _.complement() Method

The Lodash _.complement() method returns a function that reverses the sense of a given predicate-function.

Syntax:

_.complement( function );

Parameters: This method accepts a single parameter as listed above and discussed below.

• function: This parameter predicate function defined containing the returning logic.

Return Value: This method returns a function.

Note: To execute the below examples, you have to install the lodash-contrib library by using this command prompt and execute the following command.

npm install lodash-contrib

Below examples illustrate the Lodash _.complement() method in JavaScript:

Example 1:

Javascript

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

function gfgFun (x) {
    return x>=2 ;
}

var comp = _.complement(gfgFun);

var x=1000;

console.log("Without Complement Function:",gfgFun(x))

console.log("With Complement Function:",comp(x));

Output:

Without Complement Function: true
With Complement Function: false

Example 2: 

Javascript

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

function gfgFun (x) {
    return x=="Geeks" ;
}

var comp = _.complement(gfgFun);

var x="GeeksforGeeks";
console.log("Without Complement Function:",gfgFun(x))

console.log("With Complement Function:",comp(x));

Output:

Without Complement Function: false
With Complement Function: true