1.声明长度为num的数组
var 数组名字 = new Array(num);
<script>
var list = new Array(10);
console.log(list.length);
</script>
控制台输出结果为:
10
2.如果数组中有多个数值,或者第一个元素不是数值时,代表着数组内部的值
<script>
var list1 = new Array(10,'10',10);
console.log(list1.length);
var list2 = new Array('10');
console.log(list2.length);
</script>
控制台输出结果为:
3
1
3. Array.of()用法和new Array()一样,但Array.of()会把一个数值元素也当做数组内部的值
<script>
var list = Array.of(10);
console.log(list.length);
</script>
控制台输出结果为:
1
4. for in可以用来遍历数组
<script>
var list = Array.of(10,20,30,40,50);
for(var i in list){
console.log(list[i]);
}
</script>
控制台输出结果为:
10
20
30
40
50
5.Array.from()把类数组转化为数组,forEach用来遍历数组
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<button>按钮</button>
<button>按钮</button>
<button>按钮</button>
<button>按钮</button>
<button>按钮</button>
</body>
<script>
var btn = document.getElementsByTagName('button');
btn = Array.from(btn);
btn.forEach(function (element) {
console.log(element);
});
</script>
</html>
控制台输出结果为:
<button>按钮</button>
<button>按钮</button>
<button>按钮</button>
<button>按钮</button>
<button>按钮</button>