Recursively JavaScript

Recursively run JavaScript callback function on each item in an array.

Recursion happens if the item is also an array - for example, as in 2D arrays.

Other example for a recursion are arrays of objects with nested objects - for example a menu with submenus.

Installation

npm install recursively -S

Usage

var recursively = require('recursively');


/**
 * Recursively run callback on items in a Javascript array
 * @param arr               An array that can be iterated
 * @param callback          Callback will receive following arguments:
 *                          item = value or item in the collection
 *                          index = index of this item in the array
 *                          arr = original array. So one can change the original value if needed
 * @param childProperty     Optional child property. If iterated item is an object, recursion will dive into this property
 * @return void | any       If callback returns a value, it is rewriting the value in array or else it is left intact
 */
recursively(input: array, callback: (item?:any, index?:number, childProperty?:array) => void|any)

Example 1 - populating 3x3 array with incremental integers from 1 to 9

var recursively = require('recursively');

var data = [new Array(3).fill(), new Array(3).fill(), new Array(3).fill()];
var i = 1;
recursively(data, function () {
    return i++;
}           

// data will be [[1, 2, 3], [4, 5, 6], [7, 8, 9]];
    

Example 2 - populate array of 9 items with fibonacci numbers by referring to the previous item in collection

var recursively = require('recursively');

var data = new Array(9).fill();
recursively(data, function (item, index, collection) {
    if (index === 0) {
        return 0;
    } else if (index === 1) {
        return 1;
    } else {
        return collection[index - 2] + collection[index - 1];
    }
});          

// data will be [[1, 2, 3], [4, 5, 6], [7, 8, 9]];

Example 3 - enabling all objects in flat array

var recursively = require('recursively');

var data = [{enabled: false}, {enabled: false}];
recursively(data, function(item){
    item.enabled = true;
});

// data will be [{enabled: true}, {enabled: true}];
    

Example 4 - enabling first child of each submenu

var recursively = require('recursively');

var menu = [{
    title: 'Level 1',
    enabled: false,
    submenu: [
        {
            title: 'Level2 a',
            enabled: false,
            submenu: [
                {
                    title: 'Level3 aa',
                    enabled: false
                },
                {
                    title: 'Level3 ab',
                    enabled: false
                }]
        }, {
            title: 'Level2 b',
            enabled: false,
            submenu: [
                {
                    title: 'Level2 ba',
                    enabled: false
                },
                {
                    title: 'Level2 bb',
                    enabled: false
                }]
        }]
}];

function enableFirstChild(item, index) {
    if (index === 0) {
        item.enabled = true;
    }
}

recursively(menu, enableFirstChild, 'submenu');

// menu[0].enabled==true;
// menu[0].submenu[0].enabled==true;
// menu[0].submenu[0].submenu[0].enabled==true;
// menu[0].submenu[1].submenu[0].enabled==true;

Test

npm test

Contributions

welcomed.... Just make a test.