@stdlib/iter-none-by NPM

iterNoneBy

Test whether every iterated value fails a test implemented by a predicate function.

Installation

npm install @stdlib/iter-none-by

Usage

var iterNoneBy = require( '@stdlib/iter-none-by' );

iterNoneBy( iterator, predicate[, thisArg] )

Tests whether every iterated value fails a test implemented by a predicate function.

var array2iterator = require( '@stdlib/array-to-iterator' );

function predicate( v ) {
    return ( v <= 0 );
}

var arr = array2iterator( [ 1, 1, 1, 1, 1 ] );

var bool = iterNoneBy( arr, predicate );
// returns true

If a provided iterator does not return any iterated values, the function returns true.

var array2iterator = require( '@stdlib/array-to-iterator' );

function predicate() {
    return true;
}

var bool = iterNoneBy( array2iterator( [] ), predicate );
// returns true

A predicate function is provided two arguments:

value: iterated value
index: iteration index (zero-based)

To set the execution context of the predicate function, provide a thisArg.

var array2iterator = require( '@stdlib/array-to-iterator' );

function predicate( v ) {
    this.count += 1;
    return ( v <= 0 );
}

var arr = array2iterator( [ 1, 1, 0, 1, 1 ] );

var ctx = {
    'count': 0
};

var bool = iterNoneBy( arr, predicate, ctx );
// returns false

var n = ctx.count;
// returns 3

Notes

The function immediately returns upon encountering a truthy return value.

Examples

var randu = require( '@stdlib/random-iter-randu' );
var iterNoneBy = require( '@stdlib/iter-none-by' );

function threshold( r ) {
    return ( r >= 0.99 );
}

// Create an iterator which generates uniformly distributed pseudorandom numbers:
var opts = {
    'iter': 100
};
var riter = randu( opts );

// Determine if all values are below a threshold:
var bool = iterNoneBy( riter, threshold );
// returns <boolean>

console.log( bool );

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.