Question

I want to transform a string like “0800” automatically to “08:00”.

So I thought that way: If I type in the running program 2 digits, after typing the third the colon should automatically appear between the second and third digit. Without refreshing or something.

Has anyone a solution for me?

Answer 1

<input type="text" id="input" />​

<script type="text/javascript">
    document.getElementById("input").onkeydown = function(e) {
        if(e.keyCode != 8 && this.value.length == 2) {
            this.value += ":";
        }
    }​
</script>

Working demo available here.