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Object.html
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Object.html
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<!DOCTYPE html>
<html>
<head>
<title></title>
</head>
<body>
</body>
<script type="text/javascript">
//🍊object.create应于函数 new
var a = {a:3,c:4};
var t = Object.create(a);
console.log(t)
//🍎Object.prototype.toString.call 使用 对象原型的toString 是因为 大多数对象的toString 都不准确 或者没有
try{
//1.toString() //Uncaught SyntaxError: Invalid or unexpected token
console.log((true).toString())//"true" 布尔对象此方法不准确
console.log(Object.prototype.toString.call(true))
//([]).toString() //""
//{}.toString() //Uncaught SyntaxError: Unexpected token .
//null.toString() //Uncaught TypeError: Cannot read property 'toString' of null
//undefined.toString() //Uncaught TypeError: Cannot read property 'toString' of undefined
NaN.toString() //"NaN"
console.log(Object.prototype.toString.call(NaN)) //[object Number]
//这些需要刻意背一下，其中1和{}是语法错误。null和undefined是因为没有toString方法,可以使用call来借用
1..toString() //"1"
//(1).toString() //"1"
Number(1).toString() //"1"
console.log(({}).toString()) //[object Object]
console.log(([]).toString()) // 空 数组对象没有这个方法
Object.prototype.toString.call(null) //[object Null]
Object.prototype.toString.call(undefined) //[object Undefined]
console.log(Object.prototype.toString.call([])) //[object Array]
}catch(e){
console.log(e)
}
//🍌原型上的方法是可以直接调用的
function Rest(argument) {
// body...
}
Rest.prototype = {
afer:function(arg){
//console.log("afer")
return this.valueOf()
}
}
console.log(Rest.prototype.afer('10'))
</script>
</html>