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doUntil

Invoke a function until a test condition is true.

Installation

npm install @stdlib/utils-do-until

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var doUntil = require( '@stdlib/utils-do-until' );

doUntil( fcn, predicate[, thisArg ] )

Invokes a function until a predicate function returns true. Note that the predicate function is evaluated after executing fcn; thus, fcn always executes at least once.

function predicate( i ) {
    return ( i >= 5 );
}

function beep( i ) {
    console.log( 'boop: %d', i );
}

doUntil( beep, predicate );
/* =>
    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
};

doUntil( count, predicate, context );

console.log( context.count );
// => 5

Examples

var randu = require( '@stdlib/random-base-randu' );
var doUntil = require( '@stdlib/utils-do-until' );

function predicate() {
    return ( randu() <= 0.05 );
}

function log( i ) {
    console.log( i );
}

doUntil( log, predicate );

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See Also

• @stdlib/utils-async/do-until: invoke a function until a test condition is true.
• @stdlib/utils-do-until-each: until a test condition is true, invoke a function for each element in a collection.
• @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-while: invoke a function while a test condition is true.

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Notice

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.

Community

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License

See LICENSE.

Copyright

Copyright © 2016-2025. The Stdlib Authors.