Underscore.js _.mapArgs() Method

The _.mapArgs() method takes a target function and returns a new function that accepts a mapping function, which in turn returns a function that will map its arguments before calling the original target function.

Syntax:

_.mapArgs( target_function, mapping_function );

Parameters:

• target_function: Original called function.
• 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 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;
}

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

var cubethenadd = _.mapArgs(add)(cube);

console.log(cubethenadd(5))

Output:

250

Example 2:

Javascript

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

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

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

var subthenadd = _.mapArgs(add)(sub);

console.log(subthenadd(5))

Output:

0