ArrayN.js - Extended Array for Rhino

ArrayN.js

'use strict';

var ArrayN = {
    findIndex: findIndex,
    find: find,
    includes: includes,
    keyBy: keyBy,
    test: test,
};
Object.getOwnPropertyNames(Array).forEach(function(name) {
    ArrayN[name] = Array[name];
});
module.exports = ArrayN;

/**
 * Like ES6 Array.findIndex
 * @param {object[]} array 
 * @param {requestCallback} evaluator 
 */
function findIndex(array, evaluator) {
    for (let i = 0; i < array.length; i++) {
        if (evaluator(array[i])) return i;
    }
    return -1;
}

/**
 * Like ES6 Array.find
 * @param {object[]} array 
 * @param {requestCallback} evaluator 
 */
function find(array, evaluator) {
    const i = findIndex(array, evaluator);
    return i === -1 ? undefined : array[i];
}

/**
 * Like ES6 Array.includes
 * @param {object[]} array 
 * @param {object} value
 */
function includes(array, value) {
    const res = array.indexOf(value) !== -1;
    return res;
}

/**
 * Like Lodash Array.keyBy
 * @param {object[]} array 
 * @param {requestCallback|object} keyOrKeyExtractor 
 */
function keyBy (array, keyOrKeyExtractor) {
    const keyExtractor = typeof keyOrKeyExtractor == 'string' 
        ? function(obj) { return keyOrKeyExtractor in obj && obj[keyOrKeyExtractor]}
        : keyOrKeyExtractor
    const res = {};
    
    array.forEach(function (obj) {
        const key = keyExtractor(obj);
        if (key) res[key] = obj;

    });

    return res;
}

// Add breakpoints to test the result
function test() {
    const arr2 = filter([1,2,3], function(v) {return v === 1});
    const arr3 = includes([1,2,3], 2)
    const o7 = keyBy([{a: 'a1', b: 3}, {a: 'a2', b: 6}], 'a');
    return;
}