迭代器iterator
2020-03-16 本文已影响0人
小雪洁
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>迭代器iterator</title>
</head>
<body>
</body>
<script>
let names=["hxj","ydc","hwx"];
let keys =names.keys();
console.log(keys);//返回一个迭代对象
console.log(keys.next());//{value: 0, done: false}
//value值指的是索引，done值表示是否迭代完成，false表示还没迭代完
//console.log(keys.next());//{value: 1, done: false}
//console.log(keys.next());//{value: 2, done: false}
//console.log(keys.next());//{value: undefined, done: true}迭代完成
let arr=["hxj","ydc","hwx"];
//let values = arr.values();//报错？
let entries = arr.entries();
console.log(entries);//返回一个迭代对象
console.log(entries.next());//{value: Array(2), done: false}
//其中Array(2):[0,"hxj"],一个是索引，一个是值
//使用展开语法读取entries.next()里的值
//let {done,value}=entries.next();
//console.log(done,value);// [1, "ydc"]
//使用解构方法读取数组变量
let {done,value:[a,b]}=entries.next();
console.log(a,b);
</script>
</html>
