forEach

Usage

var forEach = require( '@stdlib/utils/for-each' );

forEach( collection, fcn[, thisArg ] )

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 element.
• index: collection index.
• collection: 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