<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
<style>
div{padding:20px;}
</style>
</head>
<body style="overflow:hidden;">
<script>
var each = function(arr, fn){
for(var index in arr){
fn.apply(null,[index,arr[index]]);
// fn.call(null,index,arr[index]);
}
}
var myArr = [1, 5, 6, 8];
each(myArr, function(index, item){
item++;
console.log(item)
})
</script>
</body>
</html>