forin 遍历数组和对象细节

for in

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//for in 遍历的是数组的索引 ,而不是数组的值
var arr= ["name","age","address"]
for (let key in arr ){
console.log(key);
}
//---------------------------------------
//遍历对象的时候,遍历的是对象的属性,而不是属性值
var obj = {name:"Jhon",age:14};
for(let key in obj){
console.log(key);
}