标签：turn rip ddr lin opp let 变量类型 关心 删除对象
JavaScript 的变量分为两类值，一种是原始值，一种是引用值；
原始值有：String Number Boolean Null Undefined;
引用值有：Object Funciton Array Date RegExp；
这里主要讨论狭义的对象；
一、对象的基本操作：增、删、改、查
1 <script type="text/javascript"> 2 /*
*对象，基础的变量类型
*字面量创建
*/ 3 var techer={ 4 name:"张三", 5 age:32, 6 sex:"male", 7 height:176, 8 weight:132, 9 tech:function(){ 10 console.log("i am teching javascript"); 11 }, 12 smoke:function(){//对象里面的函数叫 方法 13 console.log("i am smoking ") 14 }, 15 eat:function(){ 16 console.log("i am having dinner") 17 } 18 }; 19 //查：查询对象的name属性 20 console.log(techer.name); 21 techer.tech(); 22 //增 对象增加address属性 23 techer.address = "北京"; 24 console.log(techer); 25 //改 修改对象height属性 26 techer.height = 180; 27 console.log(techer.height); 28 29 //删 删除对象的address属性 30 // delete techer.address; 31 // delete techer.eat 32 33 </script>
a.对象中函数的访问：
1 <script type="text/javascript"> 2 var techer={ 3 name:"张三", 4 age:32, 5 sex:"male", 6 height:176, 7 weight:132, 8 tech:function(){ 9 console.log("i am teching javascript"); 10 }, 11 smoke:function(){//对象里面的函数叫 方法 12 this.weight--; 13 console.log("my weight is "+ this.weight); 14 }, 15 eat:function(){ 16 this.weight++;//方法访问属性 使用 this 17 console.log("my weight is "+ this.weight); 18 } 19 }; 20 techer.smoke();//执行smoke方法
21 techer.eat();//执行eat方法
22 </script>
23
b.对象中带参函数的访问：
<script type="text/javascript">
var attedance = {
students:[],
total:6,
join:function(name){
this.students.push(name);//这里this指代当前对象
if(this.students.length == this.total){
console.log("学生已到齐！");
}else{
console.log(name + "到课");
}
},
leave:function(name){
var idx = this.students.indexOf(name);
if( idx != -1){
this.students.splice(idx,1);
console.log(name + "早退");
}
},
classOver:function(){
this.students = [];
console.log("已下课")
}
}
//执行带参函数
attedance.join("张三");
attedance.join("李四");
attedance.join("王五");
attedance.join("赵麻子");
attedance.join("五十多分");
attedance.join("啊啊");
attedance.leave("李四");
attedance.classOver();
console.log(attedance);
</script>
二、其他方式的对象创建
/*
*对象字面量 创建方式
*/ var obj = { name : "张三", age : 35 } /*
*其他创建函数的方式系：1.统自带的构造函数；2.自定义构造函数
*/ //1.构造函数 即 可以通过new关键字 去实例化 对象 //a.系统自带的构造函数 var object = new Object();//与 对象字面量 相等 object.name = "张三"; obj.age = 34; //b.自定义构造函数 //规范是：函数名称 大驼峰 function Techer() { this.name = "bb"; this.sex = "male"; this.weight = 130; this.smoke = function() { this.weight--; console.log(" my weight is " + this.weight); } this.eat = function() { this.weight++; console.log(‘my weight is ‘ + this.weight); } } //带参数的构造函数 function Techerx(name, sex, weight) { this.name = name; this.sex = sex; this.weight = weight; this.smoke = function() { this.weight--; console.log(" my weight is " + this.weight); } this.eat = function() { this.weight++; console.log(‘my weight is ‘ + this.weight); } } //优化构造函数 相比之下的好处是，便于维护，不用关心参数的位置； function TecherY(opt) { this.name = opt.name; this.sex = opt.sex; this.weight = opt.weight; this.smoke = function() { this.weight--; console.log(" my weight is " + this.weight); } this.eat = function() { this.weight++; console.log(‘my weight is ‘ + this.weight); } } var techer1 = new Techer(); var techer2 = new Techer(); techer1.name = "aa"; console.log(techer1); console.log(techer2); techer1.smoke(); techer1.eat(); var techerx1 = new Techerx("joy", "女", 58); console.log(techerx1) var option = { name : "joy", sex : "女", weight : 58 } var techery1 = new TecherY(option); console.log(techery1)
面试一般会问对象创建的一般有哪几种方式？
三、通过构造器创建对象的解析过程：
<script type="text/javascript"> //实例化执行过程：GO: Car = function Car(){...} // car1 // car2 // AO: this:{ // color:color, // brand:brand // } //最后 默认return this; 放到 GO中 // 注意：return 原始值 无法改变return 的结果，还是 return this;,只有返回引用值，才可以改变返回类型； function Car(color,brand){ this.color = color; this.brand = brand; } var car1 = new Car("red","Benze"); var car2 = new Car("blue","BMW"); console.log(car1.color); console.log(car2.color); //同理 function Car2(color,brand){ var me = { color: color, brand: brand } return me; } var car21 = Car2("red2","Benze2"); var car22 = Car2("blue2","BMW2"); console.log(car21.color); console.log(car22.color); </script>
四、包装类
1 <script type="text/javascript"> 2 //包装类 3 //原始值没有自己的方法和属性 4 var a = 1;//原始值 5 console.log(a); 6 var b = new Number(a);//对象 这里的 Number就是包装类，系统一共提供3中包装类 Number String Boolean 7 b.len = 1; 8 b.add = function(){ 9 console.log(1); 10 } 11 console.log(b);//对象 12 //其他例子 13 var x = 123; 14 x.len = 2; //此时，系统会做的是 new Number(123).len; 然后 delete (百度各大网站都说是 没有地方保存该对象) 15 console.log(x.len);//undefined 16 var str = "123"; 17 console.log(str.length)// 其实是 new String(str).length ，string 类型 系统自带他； 18 19 var strins = "12345"; 20 strins.length = 1; 21 console.log(strins)//12345 理由同上 22 23 //特殊的:数组截断 24 var arr = [1,2,3,4,5]; 25 arr.length = 3 26 console.log(arr);//数组的截断方法[1,2,3] 27 </script>
五、对象的遍历及链式操作
a.链式操作：
1 var schedule = { 2 wakeup:function(){ 3 console.log("Running!"); 4 return this; 5 }, 6 moring:function(){ 7 console.log("go shopping"); 8 return this; 9 }, 10 noon:function(){ 11 console.log(" having a rest"); 12 return this; 13 }, 14 afternoon:function(){ 15 console.log("sutdying"); 16 return this; 17 }, 18 evening:function(){ 19 console.log("working"); 20 return this; 21 }, 22 nigth:function(){ 23 console.log("sleeping!"); 24 return this; 25 } 26 } 27 28 29 schedule.wakeup(); 30 //链式操作 31 schedule.wakeup().moring().noon().afternoon(); 32
b.循环遍历
1 var arr = [1, 2, 3, 4, 5]; 2 var car = { 3 name:‘Benz‘, 4 color:‘red‘, 5 width:‘2.5‘, 6 length:5 7 } 8 //遍历数组 9 for(var i = 0;i < arr.length; i++){ 10 console.log(arr[i]); 11 } 12 //遍历对象 13 for(var key in car){ 14 //console.log(car.key)//car.key-->car[‘key‘] -->undefined 15 console.log("key:"+car[key]) 16 } 17 18 for(var i in arr){ 19 console.log(arr[i]); 20 } 21 var myLang = { 22 No1:‘html‘, 23 No2:‘css‘, 24 No3:‘javascript‘, 25 myStudyingLang:function(num){ 26 console.log() 27 } 28 }
六、对象的属性
a.hasOwnProperty:判断当前对象有没有指定的属性
1 function Car(){ 2 this.name = "bmw"; 3 this.color = ‘red‘; 4 this.width = "2.5"; 5 this.length = "5"; 6 } 7 //设置原型上的参数 8 Car.prototype = { 9 lang:5, 10 width:2.5 11 } 12 13 var bmw = new Car(); 14 console.log(bmw.hasOwnProperty("name")); 15 for(var key in bmw){ 16 //只打印对象本身的属性，不打印原型上的属性 17 if(bmw.hasOwnProperty(key)){ 18 console.log(key+":"+bmw[key]) 19 } 20 }
b.in 和 instanceof
1 //其他判断 判断对象是否存在某个属性 (包括原型上的) 2 console.log("lang" in bmw) 3 //判断构造函数 A对象的原型到底有没有B的原型 只要有重合 都是true 4 console.log(bmw instanceof Car)
标签：turn rip ddr lin opp let 变量类型 关心 删除对象
原文地址：https://www.cnblogs.com/lixiuming521125/p/10950695.html
