Vue Object.defineProperty
https://www.bilibili.com/video/BV1Zy4y1K7SH?p=11
ES6 往对象上添加属性
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>回顾Object.defineProperty方法</title>
</head>
<body>
<script type="text/javascript">
let person = {
name:'张三',
sex:'男'
}
Object.defineProperty(person, 'age', {
value:18
})
console.log(person);
</script>
</body>
</html>
通过 Object.defineProperty 添加的属性遍历不到
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>回顾Object.defineProperty方法</title>
</head>
<body>
<script type="text/javascript">
let person = {
name:'张三',
sex:'男',
// age:18
}
Object.defineProperty(person, 'age', {
value:18
})
console.log(Object.keys(person));
console.log(person);
</script>
</body>
</html>
证明通过 Object.defineProperty 添加的属性不可枚举
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>回顾Object.defineProperty方法</title>
</head>
<body>
<script type="text/javascript">
let person = {
name:'张三',
sex:'男',
// age:18
}
Object.defineProperty(person, 'age', {
value:18
})
//console.log(Object.keys(person));
for (let key in person) {
console.log('@', person[key]);
}
console.log(person);
</script>
</body>
</html>
通过 enumerable:true 让 Object.defineProperty 添加的属性可枚举
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>回顾Object.defineProperty方法</title>
</head>
<body>
<script type="text/javascript">
let person = {
name:'张三',
sex:'男',
// age:18
}
Object.defineProperty(person, 'age', {
value:18,
enumerable:true //控制属性是否可以枚举，默认值是 false
})
//console.log(Object.keys(person));
for (let key in person) {
console.log('@', person[key]);
}
console.log(person);
</script>
</body>
</html>
可以在 console 里改变 let 声明的对象属性值
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>回顾Object.defineProperty方法</title>
</head>
<body>
<script type="text/javascript">
let person = {
name:'张三',
sex:'男',
age:18
}
// Object.defineProperty(person, 'age', {
// value:18,
// enumerable:true, //控制属性是否可以枚举，默认值是 false
// })
//console.log(Object.keys(person));
for (let key in person) {
console.log('@', person[key]);
}
console.log(person);
</script>
</body>
</html>
在 console 里通过 person.age=19 给 person.age 赋新值，然后再在 console 中通过 person.age 输出，发现值改变了
通过 Object.defineProperty 给对象添加的属性值无法被改变
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>回顾Object.defineProperty方法</title>
</head>
<body>
<script type="text/javascript">
let person = {
name:'张三',
sex:'男',
// age:18
}
Object.defineProperty(person, 'age', {
value:18,
enumerable:true, //控制属性是否可以枚举，默认值是 false
})
console.log(Object.keys(person));
for (let key in person) {
console.log('@', person[key]);
}
console.log(person);
</script>
</body>
</html>
在 console 里通过 person.age=19 给 person.age 赋新值，然后再在 console 中通过 person.age 输出，发现还是旧的值，person.age 的值并没有改变
通过 writable:true 让 Object.defineProperty 添加的属性可以被修改
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>回顾Object.defineProperty方法</title>
</head>
<body>
<script type="text/javascript">
let person = {
name:'张三',
sex:'男',
// age:18
}
Object.defineProperty(person, 'age', {
value:18,
enumerable:true, //控制属性是否可以枚举，默认值是 false
writable:true
})
console.log(Object.keys(person));
for (let key in person) {
console.log('@', person[key]);
}
console.log(person);
</script>
</body>
</html>
在 console 里通过 person.age=19 给 person.age 赋新值，然后再在 console 中通过 person.age 输出，发现值改变了
测试删除一般方式声明声明的对象属性
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>回顾Object.defineProperty方法</title>
</head>
<body>
<script type="text/javascript">
let person = {
name:'张三',
sex:'男',
age:18
}
// Object.defineProperty(person, 'age', {
// value:18,
// enumerable:true, //控制属性是否可以枚举，默认值是 false
// writable:true //控制属性是否可以被修改，默认值是 false
// })
console.log(Object.keys(person));
for (let key in person) {
console.log('@', person[key]);
}
console.log(person);
</script>
</body>
</html>
在 console 里通过 delete person.age 删除对象的属性，然后再在 console 中通过 person 输出，发现对象的 age 属性被删除了
测试删除 Object.defineProperty 添加的对象属性
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>回顾Object.defineProperty方法</title>
</head>
<body>
<script type="text/javascript">
let person = {
name:'张三',
sex:'男',
//age:18
}
Object.defineProperty(person, 'age', {
value:18,
enumerable:true, //控制属性是否可以枚举，默认值是 false
writable:true //控制属性是否可以被修改，默认值是 false
})
console.log(Object.keys(person));
for (let key in person) {
console.log('@', person[key]);
}
console.log(person);
</script>
</body>
</html>
在 console 里通过 delete person.age 删除对象的属性，然后再在 console 中通过 person 输出，发现对象的 age 属性还在，没有被删除
测试删除 Object.defineProperty 和 configurable:true 添加的对象属性
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>回顾Object.defineProperty方法</title>
</head>
<body>
<script type="text/javascript">
let person = {
name:'张三',
sex:'男',
//age:18
}
Object.defineProperty(person, 'age', {
value:18,
enumerable:true, //控制属性是否可以枚举，默认值是 false
writable:true, //控制属性是否可以被修改，默认值是 false
configurable:true
})
console.log(Object.keys(person));
for (let key in person) {
console.log('@', person[key]);
}
console.log(person);
</script>
</body>
</html>