Underscore.js _.uniqueId() Function

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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 _.uniqueId() function is an inbuilt function in Underscore.js library of JavaScript which is used to generate a globally unique id for the client-side models or the DOM elements which requires one. When a prefix is passed as an argument to this method, the id generated will be appended to it.

Syntax:

_.uniqueId( prefix )

Parameters: It accepts a single parameter as mentioned above and described below:

prefix: It is the prefix that would be appended to the id It is am optional parameter.

Return Value: This method returns a globally unique id.

Example 1:

HTML

<!DOCTYPE html> 
<html> 
  
<head> 
    <script src= 
"https://unpkg.com/underscore@1.11.0/underscore-min.js"> 
    </script> 
</head> 
  
<body> 
    <script type="text/javascript"> 
  
        // Using _.uniqueId() method  
        // with its parameter 
        console.log(_.uniqueId('gfG_')); 
        console.log(_.uniqueId('Geeks_')); 
        console.log(_.uniqueId('CS_')); 
    </script> 
</body> 
  
</html> 

Output:

gfG_1
Geeks_2
CS_3

Example 2:

HTML

<!DOCTYPE html> 
<html> 
  
<head> 
    <script src= 
"https://unpkg.com/underscore@1.11.0/underscore-min.js"> 
    </script> 
</head> 
  
<body> 
    <script type="text/javascript"> 
  
        // Using a loop 
        for (i = 3; i < 100; i *= 2) { 
  
            // Calling uniqueId method 
            // without any parameter    
            console.log(_.uniqueId()); 
        } 
    </script> 
</body> 
  
</html> 