使用JavaScript验证用户输入

Question

I need to make it so a user can ONLY type a-z0-9 into my input box. How can I make it so the user simply cannot type other characters? If this isn't possible, how can I simply check the input with regex?

Thanks!

Answer 1

If you use jQuery, there is a format plugin that does exactly what you need. Other than that, you can use onkeyup/onkeyup to call function which will validate input against regex pattern.

Answer 2

Another notable solution is this alphanumeric plugin for jquery: http://itgroup.com.ph/alphanumeric/

Simple as $('#textField').alphanumeric();

Answer 3

You can use the onKeyDown event. If you return false from your event handler, no key press event is fired and the key is "eaten".

Here are the docs from Sun: http://docs.sun.com/source/816-6408-10/handlers.htm#1120313

Answer 4

Here is a solution that's adapted a bit from this page :

window.onload = function () {
    document.forms.myForm.myField.onkeypress = keyTest;
}

function keyTest(e) 
{
    var key = window.event ? e.keyCode : e.which;
    var keychar = String.fromCharCode(key);
    reg = /[a-z0-9]/i;

    if (key != 8 && key != 9) return reg.test(keychar);
}

Answer 5

确保还对服务器执行了验证（假设有服务器部分），以防某些用户关闭了javascript。