About stdlib...
We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.
The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.
When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.
To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!
Invoke a function for each element in a collection.
import forEach from 'https://cdn.jsdelivr.net/gh/stdlib-js/utils-for-each@esm/index.mjs';Invokes a function for each element in a collection.
function log( value, index ) {
console.log( '%s: %d', index, value );
}
var arr = [ 1, 2, 3, 4 ];
forEach( arr, log );
/* =>
0: 1
1: 2
2: 3
3: 4
*/The invoked function is provided three arguments:
value: collection elementindex: collection indexcollection: input collection
Basic support for dynamic collections is provided. Note, however, that index incrementation is monotonically increasing.
function log1( value, index, collection ) {
console.log( '%s: %d', index, value );
if ( index === collection.length-1 && collection.length < 10 ) {
collection.push( index+2 );
}
}
var arr = [ 1, 2, 3, 4 ];
forEach( arr, log1 );
/* =>
0: 1
1: 2
2: 3
3: 4
4: 5
5: 6
6: 7
7: 8
8: 9
9: 10
*/
function log2( value, index, collection ) {
console.log( '%s: %d', index, value );
collection.shift();
}
arr = [ 1, 2, 3, 4 ];
forEach( arr, log2 );
/* =>
0: 1
1: 3
*/To set the function execution context, provide a thisArg.
function sum( value ) {
this.sum += value;
this.count += 1;
}
var arr = [ 1, 2, 3, 4 ];
var context = {
'sum': 0,
'count': 0
};
forEach( arr, sum, context );
var mean = context.sum / context.count;
// returns 2.5-
A
collectionmay be either anArray,Typed Array, or an array-likeObject(excludingstringsandfunctions). -
The function differs from
Array.prototype.forEachin the following ways:-
The function returns the input
collection. -
The function does not skip
undefinedelements.function log( value, index ) { console.log( '%s: %s', index, value ); } var arr = [ 1, , , 4 ]; forEach( arr, log ); /* => 0: 1 1: undefined 2: undefined 3: 4 */
-
The function provides limited support for dynamic collections (i.e., collections whose
lengthchanges during execution).
-
<!DOCTYPE html>
<html lang="en">
<body>
<script type="module">
var isEven = require( 'https://cdn.jsdelivr.net/gh/stdlib-js/assert-is-even' ).isPrimitive;
import forEach from 'https://cdn.jsdelivr.net/gh/stdlib-js/utils-for-each@esm/index.mjs';
function log( value, index, collection ) {
console.log( '%s: %d', index, value );
if ( isEven( index ) ) {
collection.shift();
} else {
collection.push( index+1 );
}
}
var arr;
var i;
arr = new Array( 100 );
for ( i = 0; i < arr.length; i++ ) {
arr[ i ] = i;
}
forEach( arr, log );
</script>
</body>
</html>@stdlib/utils-async/for-each: invoke a function once for each element in a collection.@stdlib/utils-for-each-right: invoke a function for each element in a collection, iterating from right to left.
This package is part of stdlib, a standard library with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.
For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.
See LICENSE.
Copyright © 2016-2024. The Stdlib Authors.