I have an input field in which I want to allow only number and 1 ma. How could I make it accept only single ma?

$("#my-field").on("keyup", checkKey);

function checkKey() {
    this.value = this.value.replace(/[^0-9,]/g, "");
}

I have an input field in which I want to allow only number and 1 ma. How could I make it accept only single ma?

$("#my-field").on("keyup", checkKey);

function checkKey() {
    this.value = this.value.replace(/[^0-9,]/g, "");
}

• javascript
• jquery
• validation

• write a regular expression to match on ma? – epascarello Commented Feb 21, 2017 at 22:21
• 1 Don't do this. It is user unfriendly. Colour things, or put messages, but don't make the keyboard disfunctional. – trincot Commented Feb 21, 2017 at 22:26
• You can check this post! -> stackoverflow./questions/5570820/… – gonzajf Commented Feb 21, 2017 at 22:28
• You should be more specific about the required format to match against. – ichigolas Commented Feb 21, 2017 at 22:58

1 Answer 1

You could do it like this:

function checkKey() {
    var clean = this.value.replace(/[^0-9,]/g, "")
                           .replace(/(,.*?),(.*,)?/, "$1");
    // don't move cursor to end if no change
    if (clean !== this.value) this.value = clean;
}

// demo
document.querySelector('input').oninput = checkKey;

<input>

This will remove all repeated mas, and everything between them. That is not an issue, since you press one key at a time.

Remarks

This blocking way of input validation is user unfriendly. It is better to colour things, or put messages, than to make the keyboard disfunctional.

Consider using the <input type="number"> element, which has number validation built in.

The input event is often more useful for checking for changes in the input than keyup, since changes can also be made via mouse actions and the context menu.

If you want to allow dot instead of ma, then change every , with \. in the regular expressions, as . has a special meaning in regular expressions, and must be escaped to be taken as a literal character.