Question

I understand that jquery will allow you to modify attributes with the .attr() method. There are basically two methods:

$('#element').attr('attribute', 'value') // sets the attribute
var attribute = $('#element').attr('attribute') // gets the attribute

My question is, how do you set a boolean attribute such as ‘checked’ on a checkbox or ‘multiple’ on a select tag?

I’ve tried doing the following without success:

$('#element').attr('attribute', true)
$('#element').attr('attribute', '')

All of these add the attribute but usually like this <tag attribute="attribute">.

Answer 1

Try using .prop to deal with boolean that is for supported attributes like selected/disabled/checked e.t.c

$('#element').prop('attribute', true);

from jQuery docs, (an example)

elem.checked returns true (Boolean) Will change with checkbox state

$(elem).prop("checked") returns true (Boolean) Will change with checkbox state

elem.getAttribute("checked") returns "checked" (String) Initial state of the checkbox; does not change

$(elem).attr("checked")(1.6) returns "checked" (String) Initial state of the checkbox; does not change

$(elem).attr("checked")(1.6.1+) returns "checked" (String) Will change with checkbox state

$(elem).attr("checked")(pre-1.6) returns true (Boolean) Changed with checkbox state