Underscore.js _.noop() Function

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Underscore.js is a JavaScript library that makes operations on arrays, string, objects much easier and handy.
The _.noop() function is used to return “undefined” irrespective of the arguments passed to it.

Note: It is very necessary to link the underscore CDN before going and using underscore functions in the browser. When linking the underscore.js CDN The “_” is attached to the browser as global variable.

Syntax:

_.noop();

Parameters: It takes optional parameter of any type.

Return Value: This function returns the value of type undefined.

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> 
        let str = new String(_.noop()) 
        console.log(`String is ${str}`) 
  
        let obj = new Object(_.noop()) 
        console.log(`Object is ${obj.Object}`) 
  
        let int = _.noop() 
        console.log(`Integer is ${int}`) 
  
        let arr = new Array(_.noop()) 
        console.log(`Array is ${arr[0]}`) 
    </script> 
</body> 
  
</html> 

Output:

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> 
    <script> 
        let val = undefined; 
        let val2 = _.noop(); 
  
        console.log(val === val2) 
  
        if (val == val2) 
            console.log( 
                `val and val2 are equal`); 
        else 
            console.log( 
                `val and val2 are not equal`); 
    </script> 
</body> 
  
</html> 

Output:

Example 3: Passing parameters to the _.noop() function.

<!DOCTYPE html> 
<html> 
  
<head> 
    <script src= 
"https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore-min.js"> 
    </script> 
</head> 
  
<body> 
    <script> 
        let func = (para1) => { 
            console.log(para1) 
        } 
        console.log("output: ") 
        func(_.noop("some value")); 
  
        // Pass function as parameter 
        console.log("output: ") 
        console.log(_.noop(func)) 
  
        console.log("output: ") 
        console.log(_.noop(func())) 
    </script> 
</body> 
  
</html> 