How to enable a disabled checkbox dynamically?

Question

Please see here: http://jsfiddle.net/nShQs/

Press the disable button and then the enable button. The checkbox doesn't get enabled.

HTML:

<input id="check" type="checkbox"/>
<input id="btn1" type="button" value="enable" />
<input id="btn2" type="button" value="disable" />

JS:

function enable() {
    var x = document.getElementById("check");
    alert(x.getAttribute("disabled"));
    x.setAttribute("disabled", "false");
    alert(x.getAttribute("disabled"));
}

function disable() {
    var x = document.getElementById("check");
    alert(x.getAttribute("disabled"));
    x.setAttribute("disabled", "true");
    alert(x.getAttribute("disabled"));
}
document.getElementById("btn1").addEventListener("click", enable);
document.getElementById("btn2").addEventListener("click", disable);

answer

As the answers tell it is because the disabled attribute is a boolean attribute. See here.

Answer 1

Just do

function enable() {
    document.getElementById("check").disabled= false;

}

function disable() {
     document.getElementById("check").disabled= true;
}

With this you are setting the property of the DOM element, while setting attribute presence of attribute disabled will disable the check box, so even if you do x.setAttribute("disabled", "false"); it will still be there on the element as attribute.

Demo

or you would just do:

function disable() {
    document.getElementById("check").setAttribute('disabled', 'disabled');
}

function enable() {
   document.getElementById("check").removeAttribute('disabled');
}

disabled as attribute and disabled as property are different.

Answer 2

Set the disabled property rather than the attribute (fiddle).

function enable() {
    document.getElementById("check").disabled = false;    
}

function disable() {
    document.getElementById("check").disabled = true;
}

A control will remain disabled if the disabled attribute is present at all - regardless of its value (fiddle). Setting the disabled property to false will remove the disabled attribute.