Underscore.js _.constant() Function (original) (raw)
Last Updated : 10 Jul, 2020
Underscore.js is a JavaScript library that makes operations on arrays, string, objects much easier and handy. The _.constant() function is used to create a function that returns the parameter given to it. It is almost same as _.identity() function.
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:
_.constant( object );
Parameters: This function accepts single parameter object.
Return Value: This function returns the parameter as given to the function.
Below examples illustrate the _.constant() function in Underscore.js:
Example 1:
<!DOCTYPE html>
< html >
< head >
`` < script src =
`` </ script >
</ head >
< body >
`` < script >
`` let str = "geeksforgeeks"
`` // _.constant function of underscore.js
`` let strFunc = _.constant(str);
console.log(original str is: ${str}) ``
console.log(str Function is: ${strFunc}) ``
`` // This will return true
`` console.log(str === strFunc())
`` // Both strings are exactly same
`` console.log("from str : ", str,
`` " from strFunc: ", strFunc());
`` </ script >
</ body >
</ html >
Output:
Example 2:
<!DOCTYPE html>
< html >
< head >
`` < script src =
`` </ script >
</ head >
< body >
`` < script >
`` // Creating a object
`` let obj = {
`` "a": "one",
`` "b": "two",
`` "c": "three"
`` }
`` // _.constant function of underscore.js
`` let objFunc = _.constant(obj);
console.log(original object is: ${obj}) ``
console.log(object Function is: ${objFunc}) ``
`` // This will return true
`` console.log(obj === objFunc())
`` // Both objects are exactly same
`` console.log("from obj : ", obj.a,
`` " from objFunc: ", objFunc().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 objFunc: ", objFunc().a);
`` </ script >
</ body >
</ html >
Output:
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