按键+符号上的Javascript，如何检索它

Question

Javascript on keypress + sign, how do I retrieve it

Currently I got the following script for my enter key

<script type="text/javascript">
$(document).ready(function() {
$(function(){

    $("input[type=text]").keyup(function(e){

        if(e.keyCode == "13")
        {
            var nextIndex = $(this).prop('tabindex') + 1;
            var selectedId = $(this).prop('id');
            var rowSplit = selectedId.split("_");
            var rowIn = rowSplit[1];

            if(selectedId.indexOf("big") > -1)
            {

            bigFunction(rowIn)

            $('[tabindex=' + nextIndex + ']').focus();
            }


    $("form :input").on("keypress", function(e) {
    return e.keyCode != 13;
    });


});
</script>

I want it to work for if eg

I got a text field with maxlength 4

I enter 4 random number eg 1234 and then I press the letter + sign, I want to change focus to next tabindex

How do I do it, thanks for helping so much !!

Answer 1

I might do this instead. Example only:

$('#element').keypress(function(){
  var v = $(this).val();
  if(v.charCodeAt(v.length-1) === 43){
    // + was pressed
  }
});

Answer 2

The key code is an integer, you wrote it properly the second time. But the first uses "13" .

if(e.keyCode == 13)

would probably work better. Also the + sign code is 43 (0x2B). In JavaScript you could also use the '+'.charCodeAt(0) although of course that's much longer.

Also, when you hit enter, the default button is triggered unless you cancel the default behavior as in:

    e.preventDefault();
    e.stopPropagation();

Canceling the default behavior for the + would also help to avoid having the + appear in the input.

To trigger the auto-tab feature when you have at least 4 characters (be it digits) you want to check the length of the input box value. Probably something like this with jQuery:

if($(this).val().length >= 4) ...

Otherwise it looks like you already got most of the code as required, although your code sample is currently missing a closing brace ( } ), so I'm not too sure I can help in fixing the code the way it is.