Is it possible to put read-only text inside input alongside writable text?

I want to make an input with some read-only text and some writable text. It should always say "www." at the beginning (read only) and afterwards the user should be able to write wh开发者_开发问答atever he wants. What is the easiest way to do this?

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The "easiest" way would be to have a separate element underneath (or surrounding) the input.

http://jsfiddle.net/NxWBT/

However, this'll be for presentational purposes only. If you need the www part submitted, you'll have to add it with Javascript before the form is submitted.

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On KeyDown event you can get the string an append it

function onblurwww(){
    var tb = document.getElementById('myTextBox');
    var val = tb.value;

    if (val.substr(0, 4) != 'www.')
        tb.value = 'www.' + val;
}

something like that in your keydown on the textbox.