间接上代码，大家一看就明了
<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title></head><body> <h2>call-apply-bind</h2> <script> 'use strict' Function.prototype.call = function () { // 纯es5写法 var targetFuc = this; var thisArg = arguments[ 0 ] if ( !(typeof thisArg === 'object' || typeof thisArg === 'function') ) { throw new Error( 'type error' ) } thisArg.nestFuc = targetFuc var evalString = 'thisArg.nestFuc(' for ( var i = 1; i < arguments.length; i++ ) { evalString += 'arguments[' + i + '],' } evalString += ')' console.log( evalString ) return eval( evalString ) } Function.prototype.apply = function ( thisArg, argArray ) { if ( !(typeof thisArg === 'object' || typeof thisArg === 'function') ) { throw new Error( 'type error' ) } var targetFuc = this; thisArg.nestFuc = targetFuc var evalString = 'thisArg.nestFuc(' for ( var i = 0; i < argArray.length; i++ ) { evalString += 'argArray[' + i + '],' } evalString += ')' console.log( evalString ) return eval( evalString ) } Function.prototype.bind = function () { var targetFuc = this; var slice = Array.prototype.slice var argumentsArray = slice.call( arguments ) var thisArg = argumentsArray[ 0 ] if ( !(typeof thisArg === 'object' || typeof thisArg === 'function') ) { throw new Error( 'type error' ) } return function () { targetFuc.apply( thisArg, argumentsArray.slice(1).concat( slice.call( arguments ) ) ) } } var f1 = function (x,y) { console.log( this, x, y ) } f1.call( { a: 1 }, 6, 7 ) f1.apply( { a: 1 }, [ 6, 7 ] ) var f2 = function (x,y) { console.log( this, x, y ) } f2.bind( { b:1 }, 8, 9 )() </script></body></html>