javaScript里的arr.foreach，用法
<!DOCTYPE html>
<html >
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<script>
var arr=[12,13,15];
// 当前值 下标 所在数组
arr.forEach((value,index,arrs)=>{
console.log(index+">>>>>>>"+value+" "+arrs);
})
</script>
</head>
<body>
</body>
</html>