Underscore.js _.restArguments() Function
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.
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