Underscore.js _.after() Function

0 0 1 minute read

Underscore.js is a JavaScript library that provides a lot of useful functions that help in the programming in a big way like the map, filter, invoke, etc even without using any built-in objects.

The _.after() function is an inbuilt function in Underscore.js library of JavaScript which is used to create a wrapper of function which doesn’t do anything in the beginning but from the stated count it starts calling the stated function. Moreover, it is useful in a grouping of asynchronous responses, as you need to be sure if all the async calls have ended or not before preceding.

Syntax:

_.after(count, function)

Parameters: It accepts two parameters which are specified below:

count: It is the number of counts after which the stated function will be called.
function: It is the function stated.

Return values: This method returns the count of the function called.

Example 1:

<!DOCTYPE html> 
<html> 
  
<head> 
    <script src= 
"https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore-min.js"> 
    </script> 
</head> 
  
<body> 
    <script> 
        show = () => { 
            console.log("zambiatek") 
        } 
        console.log(`Show function will run for 5 times:`) 
  
        // Calling after function 
        func = _.after(3, show); 
        func(); 
        func(); 
        func(); 
        func(); 
        func(); 
        func(); 
        func();  
    </script> 
</body> 
  
</html> 

Output:

Show function will run for 5 times:
 zambiatek
 zambiatek
 zambiatek
 zambiatek
 zambiatek

Example 2:

<!DOCTYPE html> 
<html> 
  
<head> 
    <script src= 
"https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore-min.js"> 
    </script> 
</head> 
  
<body> 
    <button id="button">button</button> 
    <script> 
        show = () => { 
            console.log("zambiatek") 
        } 
  
        // Calling after function 
        func = _.after(3, show); 
        let button = document.querySelector("#button"); 
        let Run = () => { 
            console.log(`Show function runs for 8 times:`) 
            for (let i = 0; i < 10; i++) { 
                func(); 
            } 
        } 
        button.addEventListener("click", Run)   
    </script> 
</body> 
  
</html> 

Output:

button

Show function runs for 7 times:
 zambiatek
 zambiatek
 zambiatek
 zambiatek
 zambiatek
 zambiatek
 zambiatek
 zambiatek

Here, you need to click on the button in order to see the output.

Reference: https://underscorejs.org/#after

Whether you’re preparing for your first job interview or aiming to upskill in this ever-evolving tech landscape, zambiatek Courses are your key to success. We provide top-quality content at affordable prices, all geared towards accelerating your growth in a time-bound manner. Join the millions we’ve already empowered, and we’re here to do the same for you. Don’t miss out – check it out now!