JavaScript this.checked

Question

In JavaScript, if we write the following for example:

var c = this.checked;

What is checked here? Is it just a state that tells us if a checkbox for example is checked or not? So, can we use it to check that the checkbox is also not checked?

Answer 1

Assuming this refers to a DOM element which has a checked property (e.g. a checkbox or a radio button) then the checked property will either be true if the element is checked, or false if it's not. For example, given this HTML:

<input type="checkbox" id="example">

The following line of JS will return false:

var c = document.getElementById("example").checked; //False

Note that what you've written is standard JavaScript, not jQuery. If this refers to a jQuery object rather than a DOM element, checked will be undefined because the jQuery object does not have a checked property. If this is a jQuery object, you can use .prop:

var c = this.prop("checked");