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Underscore.js _.identity() Function

  • Last Updated : 24 Dec, 2021

Underscore.js is a JavaScript library that makes operations on arrays, string, objects much easier and handy. 
The _.identity() function is used to return the exact same replica of the value given to it as the argument. This function looks useless, but is used throughout Underscore as a default iteratee.

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:

_.identity( object );

Parameters: This function accepts single parameter object.

Return Value: This function returns the value of the given parameter.

Example 1:

JavaScript




<!DOCTYPE html>
<html>
 
<head>
    <script src=
"https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore-min.js">
    </script>
</head>
 
<body>
    <script>
 
        // Creating a string
        let str = new String("GeeksforGeeks")
 
        // _.identity function of underscore.js
        let copystr = _.identity(str)
        console.log(`original string is ${str}`)
        console.log(`Identity string is ${copystr}`)
    </script>
</body>
 
</html>

Output:

Example 2:

JavaScript




<!DOCTYPE html>
<html>
 
<head>
    <script src=
"https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore-min.js">
    </script>
</head>
 
<body>
    <script>
 
        // Creating a object
        let obj = {
            "a": 1,
            "b": 2,
            "c": 3
        }
 
        // _.identity function of underscore.js
        let copyobj = _.identity(obj)
        console.log(`original object is ${obj}`)
        console.log(`Identity object is ${copyobj}`)
 
        // This will return true
        console.log(obj === copyobj)
 
        // Both objects are exactly same
        console.log("from obj : ", obj.a,
            " from copyobj: ", copyobj.a);
 
        // Made Changes in object
        obj.a = 12
 
        // Change in one object
        // reflects in another
        console.log("change in one object"
            + " reflects in another =>")
        console.log("from obj : ", obj.a,
            " from copyobj: ", copyobj.a);
    </script>
</body>
 
</html>

Output:

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