Question

What is the shortest way in jQuery (or pure JavaScript) to increment the value of an input field?

For instance

<input id="counter" type="hidden" name="counter" value="1">

so it changes to

<input id="counter" type="hidden" name="counter" value="2">

Answer 1

$('#counter').val( function(i, oldval) {
    return parseInt( oldval, 10) + 1;
});

Demo

OR

$('#counter').val( function(i, oldval) {
    return ++oldval;
});

Demo

You can wrap any one of the above code within a function and call that for further increment. For example:

function increment() {
    $('#counter').val( function(i, oldval) {
        return ++oldval;
    });
}

Now call increment() when and where you need.