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<head>
<meta charset="UTF-8">
<meta name="viewport"
content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
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<title>Document</title>
</head>
<body>
<script>
var arr = [1,2,3];
arr.four = 4;
console.log(arr);
arr.forEach(value => {
/*if(value > 2) {
break
}*/
console.log(value)//1,2,3
})
for(let i in arr) {
console.log(i); // ‘0‘ ‘1‘ ‘2‘ ‘four‘ 相当于对象的key值
console.log(arr[i]) // 1,2,3,4 相当于对象的value值
}
for (let i of arr) {
if(i > 2) {
break
}
console.log(i); // 1,2,3 数值中的每一项的值
console.log(arr[i]);//2,3,undefined 相当于arr[1],arr[2],arr[3]
}
for (let i of ‘my‘) {
console.log(i); // ‘m‘ ‘y‘
}
for (let i of arr) {
if(i > 2) {
break
}
console.log(i); // 1,2
}
</script>
</body>
</html>
总结：如果遍历数组最好用for of,遍历对象用for in
for of遍历数组和forEach遍历数组的区别：for of能用break语句，forEach不能
时间： 2024-08-28 01:11:54