allow digits only for inputs

Question

Hi there

I;m trying yo implement a javacript function which will not allow to the user to input anything else than float numbers (digits)

This is my approach but I don't know how to improve it in order to allow submition of negatives numbers also (allow '-' key) and work on IE also.

function digits_only(evt, form) {
    var evt = evt || window.event,
        targ = evt.target || evt.srcElement,
        charCode = evt.which || evt.keyCode,
        keyChar = String.fromCharCode(charCode),
        isValid = true;
    if (charCode > 13) {
        isValid = /[0-9.]/.test(keyChar);
        //if a dolt is already in input
        if (keyChar === '.' && /\./.test(targ.value)) {
            isValid = false;
        }
    }
    return isValid;
}

Answer 1

HI, Is this a good approach? What happens if the user copies or drags some text into the input box. I think you should better do validation on submit event.

Answer 2

Is this on an asp.net web application? You could use the AjaxControlToolkits MaskEditExtender...

Answer 3

I have asking similar question here:
http://stackoverflow.com/questions/657492/restrict-user-input-using-javascript

but no one give the exact answer for the problem, so let's wait until WebForms 2.0 released

Answer 4

I think you are looking for so called "input masks". They are a lot more powerful then just allowing numbers. But you can surly use them for that. Google "javascript input mask" or check out this jQuery Plugin.

EDIT: Seems like the linked plugin only supports fixed length masks, but the term may be a good starting point...