JS for loop closure problem

For a simple example, if you want to loop through the output of each value in the array, we can use the for loop to output for example:

<script type= "Text/javascript" >var arr=["a", "B", "C", "D", "E"];for (var i=0;i<arr.length;i++) {    document.write (Arr[i]);} </script>

This is the most common one, I loop from 0 to 5 of the array of 5 values are output, where I is exactly the subscript of arr array, so loop out ~ but look at the following example will be different from what we think

As[i].onclick = function () {



}
</script>

This time will always pop-one, because the function (Onclick=function () {}) does not have this variable at all, in other words I cannot be called in this function, because there is no input value, so JS will go back to the parent to find this I variable, When I was found this for loop has actually been circulating, so I was the border town-1 so every time the pop-up is 1, to solve the problem is also simple, with the form of a closed packet can be the code as follows:

<a href= "#" >text</a> <br> <a href= "#" >link</a> <script type= "Text/javascript" > var as = document.getElementsByTagName (' a '); for (var i = as.length; i--;) 　　　　{As[i].onclick = (function () {alert (i); 　　return false; }) (i);} </script>

This allows you to pass I as a parameter to the inside of the function used.

JS for loop closure problem