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Invoke a function while a test condition is true.
To use in Observable,
whilst = require( 'https://cdn.jsdelivr.net/gh/stdlib-js/utils-while@umd/browser.js' )To vendor stdlib functionality and avoid installing dependency trees for Node.js, you can use the UMD server build:
var whilst = require( 'path/to/vendor/umd/utils-while/index.js' )To include the bundle in a webpage,
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/utils-while@umd/browser.js"></script>If no recognized module system is present, access bundle contents via the global scope:
<script type="text/javascript">
(function () {
window.whilst;
})();
</script>Invokes a function until a predicate function returns false.
function predicate( i ) {
return ( i < 5 );
}
function beep( i ) {
console.log( 'boop: %d', i );
}
whilst( predicate, beep );
/* =>
boop: 0
boop: 1
boop: 2
boop: 3
boop: 4
*/Both the predicate function and the function to invoke are provided a single argument:
- i: iteration number (starting from zero).
To set the function execution context for the invoked function, provide a thisArg.
function predicate( i ) {
return ( i < 5 );
}
function count() {
this.count += 1;
}
var context = {
'count': 0
};
whilst( predicate, count, context );
console.log( context.count );
// => 5<!DOCTYPE html>
<html lang="en">
<body>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/random-base-randu@umd/browser.js"></script>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/utils-while@umd/browser.js"></script>
<script type="text/javascript">
(function () {
function predicate() {
return ( randu() > 0.05 );
}
function log( i ) {
console.log( i );
}
whilst( predicate, log );
})();
</script>
</body>
</html>@stdlib/utils-do-until: invoke a function until a test condition is true.@stdlib/utils-do-while: invoke a function while a test condition is true.@stdlib/utils-until: invoke a function until a test condition is true.@stdlib/utils-async/while: invoke a function while a test condition is true.@stdlib/utils-while-each: while a test condition is true, invoke a function for each element in a collection.
This package is part of stdlib, a standard library for JavaScript and Node.js, 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 © 2016-2025. The Stdlib Authors.
