1. ES5实现 ```javascript (function(){ if (!Function.prototype.bind) { let slice = Array.prototy.slice

      1.  Funcion.prototype.bind = function() {

      let that = this; let context = arguments[0]; if (typeof that !== ‘function’) {

      1.    throw new TypeError("Function.prototype.bind - what is trying to be bound is not callable")

      }

      1.  let outerArgs = slice.call(arguments, 1);

      return function() {

      1.    let innerArgs = slice.call(arguments);
      2.  let allArgs = outerArgs.concat(innerArgs);
      3.  return context.apply(that, allArgs)

      ; }

      } } })()

    2. 2. ES6实现
    4. ```javascript
    5. (function() {
    6.     if(!Function.prototype.bind) {
    7.       Function.prototype.bind = function(context, ...outerArgs) {
    8.         let that = this;
    9.       if(typeof that !== 'function') {
    10.          throw new TypeError("Function.prototype.bind - what is trying to be bound is not callable");
    11.       }
    12.       return function(innerArgs) {
    13.         return that.apply(context, [...outerArgs, ...innerArgs]);
    14.       }
    15.     }
    16.   }
    17. })()