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(function() { // 代码 })();
function f1() { var N = 0; // N是f1函数的局部变量 function f2() { // f2是f1函数的内部函数,是闭包 N += 1; // 内部函数f2中使用了外部函数f1中的变量N console.log(N); } return f2; } var result = f1(); result(); // 输出1 result(); // 输出2 result(); // 输出3
function Product() { var name; this.setName = function(value) { name = value; }; this.getName = function() { return name; }; } var p = new Product(); p.setName("Fundebug"); console.log(p.name); // 输出undefined console.log(p.getName()); // 输出Fundebug
var module = (function() { var N = 5; function print(x) { console.log("The result is: " + x); } function add(a) { var x = a + N; print(x); } return { description: "This is description", add: add }; })(); console.log(module.description); // 输出"this is description" module.add(5); // 输出“The result is: 10”
var user = { name: "Rahul Mhatre", whatIsYourName: function() { console.log(this.name); } }; user.whatIsYourName(); // 输出"Rahul Mhatre", var user2 = { name: "Neha Sampat" }; user.whatIsYourName.call(user2); // 输出"Neha Sampat"
var user = { greet: "Hello!", greetUser: function(userName) { console.log(this.greet + " " + userName); } }; var greet1 = { greet: "Hola" }; user.greetUser.call(greet1, "Rahul"); // 输出"Hola Rahul" user.greetUser.apply(greet1, ["Rahul"]); // 输出"Hola Rahul"
var user = { greet: "Hello!", greetUser: function(userName) { console.log(this.greet + " " + userName); } }; var greetHola = user.greetUser.bind({greet: "Hola"}); var greetBonjour = user.greetUser.bind({greet: "Bonjour"}); greetHola("Rahul") // 输出"Hola Rahul" greetBonjour("Rahul") // 输出"Bonjour Rahul"
function addMethod(object, name, f) { var old = object[name]; object[name] = function() { // f.length为函数定义时的参数个数 // arguments.length为函数调用时的参数个数 if (f.length === arguments.length) { return f.apply(this, arguments); } else if (typeof old === "function") { return old.apply(this, arguments); } }; } // 不传参数时,返回所有name function find0() { return this.names; } // 传一个参数时,返回firstName匹配的name function find1(firstName) { var result = []; for (var i = 0; i < this.names.length; i++) { if (this.names[i].indexOf(firstName) === 0) { result.push(this.names[i]); } } return result; } // 传两个参数时,返回firstName和lastName都匹配的name function find2(firstName, lastName) { var result = []; for (var i = 0; i < this.names.length; i++) { if (this.names[i] === firstName + " " + lastName) { result.push(this.names[i]); } } return result; } var people = { names: ["Dean Edwards", "Alex Russell", "Dean Tom"] }; addMethod(people, "find", find0); addMethod(people, "find", find1); addMethod(people, "find", find2); console.log(people.find()); // 输出["Dean Edwards", "Alex Russell", "Dean Tom"] console.log(people.find("Dean")); // 输出["Dean Edwards", "Dean Tom"] console.log(people.find("Dean", "Edwards")); // 输出["Dean Edwards"]
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