[javascript] Add attribute 'checked' on click jquery

I've been trying to figure out how to add the attribute "checked" to a checkbox on click. The reason I want to do this is so if I check off a checkbox; I can have my local storage save that as the html so when the page refreshes it notices the checkbox is checked. As of right now if I check it off, it fades the parent, but if I save and reload it stays faded but the checkbox is unchecked.

I've tried doing $(this).attr('checked'); but it does not seem to want to add checked.

EDIT: After reading comments it seems i wasn't being clear. My default input tag is:

<input type="checkbox" class="done">

I need it top be so when I click the checkbox, it adds "checked" to the end of that. Ex:

<input type="checkbox" class="done" checked>

I need it to do this so when I save the html to local storage, when it loads, it renders the checkbox as checked.

$(".done").live("click", function(){
if($(this).parent().find('.editor').is(':visible') ) {
var editvar = $(this).parent().find('input[name="tester"]').val();
$(this).parent().find('.editor').fadeOut('slow');
$(this).parent().find('.content').text(editvar);
$(this).parent().find('.content').fadeIn('slow');
}
if ($(this).is(':checked')) {
$(this).parent().fadeTo('slow', 0.5);
$(this).attr('checked'); //This line
}else{

$(this).parent().fadeTo('slow', 1);
$(this).removeAttr('checked');
}
});

use this code

var sid = $(this);
sid.attr('checked','checked');

If .attr() isn't working for you (especially when checking and unchecking boxes in succession), use .prop() instead of .attr().

A simple answer is to add checked attributes within a checkbox:

$('input[id='+$(this).attr("id")+']').attr("checked", "checked");

$( this ).attr( 'checked', 'checked' )

just attr( 'checked' ) will return the value of $( this )'s checked attribute. To set it, you need that second argument. Based on <input type="checkbox" checked="checked" />

Edit:

Based on comments, a more appropriate manipulation would be:

$( this ).attr( 'checked', true )

And a straight javascript method, more appropriate and efficient:

this.checked = true;

Thanks @Andy E for that.