Underscore.js _.restArguments() Function (original) (raw)
Last Updated : 25 Nov, 2021
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 _.restArguments() function is an inbuilt function in Underscore.js library of JavaScript which is used to find a version of the function which when invoked can receive all the arguments from and beyond the stated startIndex that is collected into a single array. The number of arguments to the function would be used to determine the startIndex when a definite value is not given.
Syntax:
_.restArguments( function, startIndex )
Parameters: This method accepts two parameters as mentioned above and described below:
- function: It is the stated function.
- startIndex: It is the start position of the rest parameter. It is an optional parameter.
Return Value: This method returns a version of the function which is when invoked can receive all the arguments from and beyond the stated index.
Example 1: In this example, a user-defined function is used.
HTML
<!DOCTYPE html>
< html >
< head >
`` < script src =
`` </ script >
</ head >
< body >
`` < script type = "text/javascript" >
`` // Calling restArguments method
`` // with its parameter
`` var writes =
`` _.restArguments(function (authors, portal) {
`` return authors + portal;
`` });
`` // Calling write with its values
`` console.log(
`` writes(
`` ['Nidhi1352', ' GeeksforGeeks!']
`` )
`` );
`` </ script >
</ body >
</ html >
Output:
Nidhi1352, GeeksforGeeks!
Example 2: In this example, a starting index is passed along with the user-defined function.
HTML
<!DOCTYPE html>
< html >
< head >
`` < script src =
`` </ script >
</ head >
< body >
`` < script type = "text/javascript" >
`` // Calling restArguments method
`` // with its parameter
`` var writes =
`` _.restArguments(
`` function (authors, portal, articles) {
`` return authors + portal + articles;
`` }, [2]);
`` // Calling writes with its values
`` console.log(
`` writes(
`` ['Nidhi1352', ' GeeksforGeeks!', ' 700 ']
`` )
`` );
`` </ script >
</ body >
</ html >
Output:
Nidhi1352, GeeksforGeeks!, 700 undefined
Example 3:
HTML
<!DOCTYPE html>
< html >
< head >
`` < script src =
`` </ script >
</ head >
< body >
`` < script type = "text/javascript" >
`` var call =
`` _.restArguments(function (who, whom) {
`` return who + ' ' +
`` _.initial(whom).join(', ') +
`` (_.size(whom) > 2 ? ', & ' : '') +
`` _.last(whom);
`` });
`` // Calling the function above
`` // with its values
`` console.log(
`` call(
`` 'She called', 'me', 'her', 'you.'
`` )
`` );
`` </ script >
</ body >
Output:
She called me, her, & you.