1. 对象没有length属性
2.Array.prototype.slice.call(obj)能将具有length属性的对象转成数组，不带length属性的对象，只能声明数组去转换
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// 1. 对象没有length属性
// Array.prototype.slice.call(obj)能将具有length属性的对象转成数组，不带length属性的对象，只能声明数组去转换
let obj = {0: 'a', 1: 'b', 2:'c',length:3};
let obj1 = {0: 'a', 1: 'b', 2:'c'};
let arr = Array.from(obj); // ['a','b','c'];
var arr2=[];
for(var i in obj){
arr2.push(obj[i]);
}
var arr3= Array.prototype.slice.call(obj)
console.log(arr,arr2,arr3);
//会输出undefined，因为对象是没有length属性的。
// console.log(obj1.length);
function test(a, b, c, d) {
var arg = Array.prototype.slice.call(arguments, 1);
alert(arg);
}
test("a", "b", "c", "d"); //b,c,d
//通用的转化数组的方法
var toArray = function (s) {
if (s.length) {
return Array.prototype.slice.call(s);
}
else {
var arr = [];
for (var i in s) {
arr[i] = s[i];
//or
// arr.push(s[i]);
}
return arr;
}
}
console.log(toArray(obj1));
var t={
id:2,
name:"zain",
sex:'男'
};
console.log(toArray(t));
console.log(t['name'],t.name);
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