Underscore.js _.unsplatl() Method

The _.unsplatl() method takes a function expecting an array as its first argument and returns a function which works identically, but takes list of leading arguments. It is similar to the unsplat() method. It mimics the rest parameter syntax in ECMAScript 6.

Syntax:

_.unsplatl( function )

Parameters:

• function: It is the original function that takes its first argument as an array.

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. The Underscore.js contrib library can be installed using npm install underscore-contrib –save.

Example 1:

Javascript

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

// Function that takes array as the
// first parameter
function g(arr, val) {
  return val + " : " + arr;
}

// Using the unsplatl() method
var gfgFunc = _.unsplatl(g);

console.log(gfgFunc(1, 2, 3, 4, "A"));

Output:

A : 1,2,3,4

Example 2: 

Javascript

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

// Function that takes array as the
// first parameter
function g(arr) {
  return arr;
}

// Using the unsplatl() method
var gfgFunc = _.unsplatl(g);

console.log(gfgFunc(1, 2, 3, 4));

Output:

[ 1, 2, 3, 4 ]

Example 3: 

Javascript

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

// Function that takes array as the
// first parameter
function g(arr, val) {
  return arr.join(val);
}

// Using the unsplatl() method
var gfgFunc = _.unsplatl(g);

console.log(
  gfgFunc("GeeksforGeeks",
  "Computer Science Portal for Geeks", " : ")
);

Output:

GeeksforGeeks : Computer Science Portal for Geeks