locutus/esm/php/array/array_filter.js

Locutus other languages' standard libraries to JavaScript for fun and educational purposes

export function array_filter(arr, func) {
    //  discuss at: https://locutus.io/php/array_filter/
    // original by: Brett Zamir (https://brett-zamir.me)
    //    input by: max4ever
    // improved by: Brett Zamir (https://brett-zamir.me)
    //      note 1: Takes a function as an argument, not a function's name
    //   example 1: var odd = function (num) {return (num & 1);}
    //   example 1: array_filter({"a": 1, "b": 2, "c": 3, "d": 4, "e": 5}, odd)
    //   returns 1: {"a": 1, "c": 3, "e": 5}
    //   example 2: var even = function (num) {return (!(num & 1));}
    //   example 2: array_filter([6, 7, 8, 9, 10, 11, 12], even)
    //   returns 2: [ 6, , 8, , 10, , 12 ]
    //   example 3: array_filter({"a": 1, "b": false, "c": -1, "d": 0, "e": null, "f":'', "g":undefined})
    //   returns 3: {"a":1, "c":-1}
    const callback = func || ((v) => v);
    if (Array.isArray(arr)) {
        // @todo: Issue #73
        const filtered = [];
        for (const [key, value] of Object.entries(arr)) {
            const numericKey = Number(key);
            if (Reflect.apply(callback, undefined, [value, numericKey])) {
                filtered[numericKey] = value;
            }
        }
        return filtered;
    }
    const filtered = {};
    for (const [key, value] of Object.entries(arr)) {
        if (Reflect.apply(callback, undefined, [value, key])) {
            filtered[key] = value;
        }
    }
    return filtered;
}