javascript limit text input characters

Question

I am wanting to restrict the input characters for a text box to [a-z0-9_-]. However whenever if do this buttons like backspace and the arrow keys don\'t work. I have found s

Answer 1

Add this code to onkeypress event.

    var code;
    document.all ? code = e.keyCode : code = e.which;
    return ((code > 64 && code < 91) || (code > 96 && code < 123) || code == 8 || code == 32 || (code >= 48 && code <= 57));

For browser compatibility, You can add var k = e.keyCode == 0 ? e.charCode : e.keyCode;