flavor-js/src/Extensions/function.js

FlavorJS the definitive JS natives chainable extensions methods (based on lodash & ES6)

import _ from 'lodash';

/**
 * @namespace function
 * @description the JS native Function class
 */
export default {
  native: {
    /**
     * checked if something is a function
     * @example <caption>eg. usage</caption>
     * var f = function(){};
     *
     * console.log(Function.isFunction(f)); // true
     *
     * console.log(Function.isFunction(2)); // false
     *
     * console.log(Function.isFunction(function(){})); // true
     *
     * console.log(Function.isFunction(null)); // false
     * @memberOf function
     * @method isFunction
     * @instance
     * @param {function} f - the function to be checked
     * @return {boolean}
     */
    isFunction(f) {
      return Function.prototype.isFunction.call(f);
    },

    /**
     * proxies a function with scope and optional arguments<br><br>
     * @example <caption>eg. usage</caption>
     * var a = 1;
     * var b = new Date();
     * var c = function() {};
     *
     * var scope = {
       *   prop1: 2.53,
       *   prop2: 'foo';
       * };
     *
     * var f = function(a, b, c) {
       *   console.log(this.prop1, a, b, c);
       * }
     *
     * f(a, b, c);
     * // it logs
     * undefined, 1, Date, function()
     *
     * var pf = f.proxy(scope);
     * pf(a, b, c);
     * // it logs
     * 2.53, 1, Date, function()
     *
     * pf = f.proxy(scope, 2, null);
     * pf(a, b, c);
     * // it logs
     * 2.53, 2, null, function()
     * @memberOf function
     * @method proxy
     * @instance
     * @param {function} f - the function to be proxed
     * @param {object} scope - the scope object (will be `this` inside the function)
     * @param {...object} args - pass one or more arguments to override the original handled arguments
     * @return {function}
     */
    proxy(f, scope, ...args) {
      return Function.prototype.proxy.call(f, scope, ...args);
    },
  },
  prototype: {
    isFunction() {
      return _.isFunction(this);
    },

    proxy(scope, ...proxyArgs) {
      const func = this;

      return function (...args) {
        return func.apply(scope, (proxyArgs.length >= 1 ? proxyArgs : args));
      };
    },
  },
};