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Test whether all elements in a collection pass a test implemented by a predicate function.
npm install @stdlib/utils-every-byAlternatively,
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umdbranch (see README).
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var everyBy = require( '@stdlib/utils-every-by' );Tests whether all elements in a collection pass a test implemented by a predicate function.
function isPositive( value ) {
return ( value > 0 );
}
var arr = [ 1, 2, 3, 4 ];
var bool = everyBy( arr, isPositive );
// returns trueIf a predicate function returns a non-truthy value, the function immediately returns false.
function isPositive( value ) {
return ( value > 0 );
}
var arr = [ 1, -2, 3, 4 ];
var bool = everyBy( arr, isPositive );
// returns falseThe invoked function is provided three arguments:
- value: collection element.
- index: collection index.
- collection: input collection.
To set the function execution context, provide a thisArg.
function sum( value ) {
if ( value < 0 ) {
return false;
}
this.sum += value;
this.count += 1;
return true;
}
var arr = [ 1, 2, 3, 4 ];
var context = {
'sum': 0,
'count': 0
};
var bool = everyBy( arr, sum, context );
// returns true
var mean = context.sum / context.count;
// returns 2.5-
A
collectionmay be either anArray,Typed Array, or an array-likeObject(excludingstringsandfunctions). -
If provided an empty collection, the function returns
true.function untrue() { return false; } var bool = everyBy( [], untrue ); // returns true
-
The function differs from
Array.prototype.everyin the following ways:-
The function does not skip
undefinedelements.function log( value, index ) { console.log( '%s: %s', index, value ); return true; } var arr = [ 1, , , 4 ]; var bool = everyBy( 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).
-
var randu = require( '@stdlib/random-base-randu' );
var everyBy = require( '@stdlib/utils-every-by' );
function isPositive( value ) {
return ( value > 0 );
}
var bool;
var arr;
var i;
arr = new Array( 100 );
for ( i = 0; i < arr.length; i++ ) {
arr[ i ] = randu();
}
bool = everyBy( arr, isPositive );
// returns <boolean>@stdlib/utils-any-by: test whether at least one element in a collection passes a test implemented by a predicate function.@stdlib/utils-every-by-right: test whether all elements in a collection pass a test implemented by a predicate function, iterating from right to left.@stdlib/utils-for-each: invoke a function for each element in a collection.@stdlib/utils-none-by: test whether all elements in a collection fail a test implemented by a predicate function.@stdlib/utils-some-by: test whether a collection contains at leastnelements which pass a test implemented by a predicate function.
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 © 2016-2024. The Stdlib Authors.
