jquery - validate characters on keypress?

Question

I have a form text field that I want to allow only numbers and letters in. (i.e., no #$!, etc...) Is there a way to throw up an error and prevent the keypress from actuall

Answer 1

I found that combining validation on keypress and keyup gives the best results. Key up is a must if you want to handle copy pasted text. It is also a catch all in case of cross browser issues which allow non numeric values into your textbox.

    $("#ZipCode").keypress(function (event) {

        var key = event.which || event.keyCode; //use event.which if it's truthy, and default to keyCode otherwise

        // Allow: backspace, delete, tab, and enter
        var controlKeys = [8, 9, 13];
        //for mozilla these are arrow keys
        if ($.browser.mozilla) controlKeys = controlKeys.concat([37, 38, 39, 40]);

        // Ctrl+ anything or one of the conttrolKeys is valid
        var isControlKey = event.ctrlKey || controlKeys.join(",").match(new RegExp(key));

        if (isControlKey) {return;}

        // stop current key press if it's not a number
        if (!(48 <= key && key <= 57)) {
            event.preventDefault();
            return;
        }
    });

$('#ZipCode').keyup(function () {
    //to allow decimals,use/[^0-9\.]/g 
    var regex = new RegExp(/[^0-9]/g);
    var containsNonNumeric = this.value.match(regex);
    if (containsNonNumeric)
        this.value = this.value.replace(regex, '');
});