Underscore.js _.mapArgsWith() Method

The _.mapArgsWith() method takes a mapping function and returns a new combinator function which will take a target function and will return a new function that maps its arguments with the mapping function before executing the body of the target function.

Syntax:

_.mapArgsWith( mapping_function );

Parameters:

• mapping_function: Mapping function to be accepted by the function.

Return Value: This method returns a function.

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: We made a function that cubes the given value then adds that value to itself.

Javascript

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

function add (x) {
    return x + x + x ;
}

function sub (x) {
    return  x - 2;
}

var addnow = _.mapArgsWith(sub);

var subnow = addnow(add);

console.log(subnow(5))

Output:

9

Example 2:

Javascript

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

function squ (x) {
    return x * x ;
}

function add (x) {
    return  x + 10;
}

var addnow = _.mapArgsWith(add);

var sq = addnow(squ);

console.log(sq(5))

Output:

225

Example 3:

Javascript

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

function cs (x) {
    return
"GeeksforGeeks : Computer Science Portal for Geeks";
}

function geek (x) {
    return  "GeeksforGeeks";
}

var gfg = _.mapArgsWith(geek);

var gfgFunc = gfg(cs);

console.log(gfgFunc())

Output:

GeeksforGeeks : Computer Science Portal for Geeks

Example 4:

Javascript

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

function cs (x) {
    return x;
}

function geek (x) {
    return  x[0]+" : "+x[1];
}

var gfg = _.mapArgsWith(geek);

var gfgFunc = gfg(cs);

console.log(gfgFunc(["GeeksforGeeks",
    "Computer Science Portal for Geeks"]))

Output:

GeeksforGeeks : Computer Science Portal for Geeks