Number input shortcut key incrementers and decrementers

Question

Is there a way to detect when a value in a number field is being increased or decreased? I would like that to determine wether or not to add or subtract an extra amount eg shit is down so +5 if increasing etc.

I have:

var oldVal = input.val();
input.change(function() {
    var newVal = input.val();
    if (newVal > oldVal) {
        if (shiftIsDown) {
            input.val(parseInt(input.val()) + 5);
        }
    }
    if (newVal < oldVal) {
        if (shiftIsDown) {
            input.val(parseInt(input.val()) - 5);
        }
    }
    oldVal = newVal;
})

But it behaves strangely and does'nt really work.

Answer 1

Try something like

var oldVal = input.val();
input.change(function(e) {
 var newVal = input.val();
 var shiftIsDown = e.shiftKey ? true : false;
 if(shiftIsDown) {
    if(newVal > oldVal)
        input.val(parseInt(input.val()) + 5);
    else if (newVal < oldVal)
        input.val(parseInt(input.val()) - 5);
 }
 oldVal = newVal;
})

assuming input is a jquery object.

Answer 2

Look at this Fiddle :

var input = $("#input");
var oldVal = input.val();
var newVal = input.val();

input.keyup(function () {
    oldVal = newVal;
    newVal = input.val();
});

$(document).keydown(function (e) {
    if (e.keyCode == 16) {
            if (newVal > oldVal) {
            input.val(parseInt(input.val()) + 5);
    }
    if (newVal < oldVal) {
            input.val(parseInt(input.val()) - 5);
    }
    }
});

keyup function is for listening of input changes

keydown functions is for shift down listening - (e.keyCode == 16) is equals to pressing shift event, so when you ever press shift the input val is being changing