Allow value -1 when clicking on a button and link, but just one time (the first time clicked upon) without disabling the button/link

Question

I have the following script:

<script language=javascript>
    function process(v){
        var value = parseInt(document.getElementById('v').value);
        value+=v;
        document.getElementById('v').value = value;
    }
</script>


<input type=test size=10 id='v' name='v' value='3'>
<input type=button value='-' onclick='javascript:process(-1)'>
<a id="v" href="#" onclick='javascript:process(-1)'>minus</a>

If you click the button, it will deduct 1 from the total amount (3). The same applies for the minus-link. Now this all works great.

The problem is that I want to allow each one to deduct 1, just one time. Without disabling the button/link.

Example what I need: So I click the button: 3 -> 2. Now I click the button again, nothing will happen 2 stays 2. Now I click the minus-link, 2 -> 1. Clicking the link again, nothing will happen 1 stays 1

This can all be mixed of course. The main thing is, they each are allowed to do the -1 just one time (the first time clicked upon).

How to do this?

Kind regards, Maurice

Answer 1

First: You don't need the javascript: -prefix in an onclick attribute.

You can achieve your desired behaviour by removing the onclick method on click, as shown below, and in this fiddle: http://jsfiddle.net/XPHLU/1/

<script>
function process(v, elem){
    if(elem && elem.onclick){
        elem.onclick = null;
    }
    var value = parseInt(document.getElementById('v').value);
    value+=v;
    document.getElementById('v').value = value;
}
</script>

<input type=test size=10 id='v' name='v' value='3'>
<input type=button value='-' onclick='process(-1, this);'>
<a id="v" href="#" onclick='process(-1, this)'>minus</a>

Answer 2

<script language=javascript>
$(document).ready(function(){

    $("#negativeButton, #v").one("click", {arg: -1}, function(event){
//.one() registers a 'click' event, execute it once, and unbind it.  
//stop propagation to the other click events.      
        event.stopImmediatePropagation();
//stop from moving to href="" 
        event.preventDefault();
        process(event.data.arg, this);
    });
//optionally, you can register a .click() after this as well for the same buttons.  .one() will only remove that 'one' click event.

});
    function process(v){
        var value = parseInt(document.getElementById('v').value);
        value+=v;
        document.getElementById('v').value = value;
    }
</script>


<input type=test size=10 id='v' name='v' value='3'>
<input id="negativeButton" type="button" value='-' >
<a id="v" href="#">minus</a>

Answer 3

Since this question is tagged under jQuery, I provide you a way do do it in jQuery! Using this could help you in the long run to get a cleaner code and to fix future problems like this ;)

Demo: http://jsfiddle.net/NtHwN/4/

<input size=10 id="sum" value="3">
<input class="minus" type=button value="-">
<a class="minus" href="#">minus</a>

$(document).ready(function() {
    $(".minus").one("click", function(){
        var value = parseInt($("#sum").val());
        $("#sum").val(value -1);
    });
});

Answer 4

<input type=button value='-' onclick='javascript:process(-1)' id="button-to-click">

Remove the click handler:

   function process(v){
     var value = parseInt(document.getElementById('v').value);
     value+=v;
     document.getElementById('v').value = value;
     document.getElementById('button-to-click').onclick = null;
    }

or for multiple

<input type=button value='-' onclick='javascript:process(this, -1)'>

Remove the click handler:

   function process(obj, v){
     var value = parseInt(document.getElementById('v').value);
     value+=v;
     document.getElementById('v').value = value;
     obj.onclick = null;
    }

Answer 5

Well... this one should work. JSFiddle is here .

HTML (with minor changes):

<input type=test size=10 id='v' name='v' value='3'></input>
<input id="i" type=button value='Minus'></button>
<a id="l" href="javascript://">minus</a>

Note: I do not necessarily recommend using javascript:// .

JavaScript:

function appendEvent(id) {
    document.getElementById(id).addEventListener('click', (function() {
        var clicked = false;
        var inputEl = document.getElementById('v');
        return function() {
            if (!clicked) {
                var value = parseInt(inputEl .value);
                inputEl.value = --value;
                clicked = true;
            };
        };
    }()));
}

appendEvent('i');
appendEvent('l');