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jQuery v1.6 Checkbox issue

attr() vs prop()

I have been visiting Stackoverflow a lot recently. This is a cool forum where you not only get your questions answered but also learn. Learn a lot, in fact. I always enjoy learning from others’ experience and mistakes; it’s dirty but it is also very easy and fast. This is exactly what Stackoverflow is providing me; an opportunity to learn from others’ knowledge. I’m also having fun with their reputation points.

I was trying to answer this question (which deals with a master and a number of checkboxes) and came up with a code which worked only in jQuery version <1.6

// Code that works with <1.6; uses attr()
$(function () {
    $("#checkall").click(function () {
        $(this).parents("fieldset:eq(0)").find(":checkbox").attr("checked", this.checked);
        if(!this.checked) {
            // at least one is unchecked; uncheck checkall
            $("#checkall").attr("checked", this.checked);
        } else {
            // check if all are checked and set checkall accordingly


After a couple of minutes of tinkering, it just occurred to me that this was due to the prop method that I read about a day or two earlier. Just changing the attr to prop worked like a charm.

However, I didn’t know how to fix it and this is where the community knowledge came to the rescue. A user named Matt Ball pointed me to his jQuery-CheckAll plugin and asked me to take a look.

The fix was/is to check if prop exists or not and use it if it does. Notice the syntax of calling the prop/attr method in below code.

// Code that works with any version; uses attr()/prop()
$(function() {
    // Ripped from
    var propFn = typeof $.fn.prop === "function" ? "prop" : "attr";

    $("#checkall").click(function() {
        $(this).parents("fieldset:eq(0)").find(":checkbox")[propFn]("checked", this.checked);
    $("input[type=checkbox]:not(#checkall)").click(function() {
        if (!this.checked) {
            // at least one is unchecked; uncheck checkall
            $("#checkall")[propFn]("checked", this.checked);
        } else {
            // check if all are checked and set checkall accordingly
            $("#checkall")[propFn]("checked", !$("input[type=checkbox]:not(#checkall)").filter(":not(:checked)").length);


My answer to that question - here. Read more about prop() in v1.6 here.

    <div class="radio"><input type="checkbox" name="checkall" id="checkall"> <label for="checkall">Check all</label></div>
    <div class="radio"><input type="checkbox" name="checkbox1" id="checkbox1"> <label for="checkbox1">Checkbox</label></div>
    <div class="radio"><input type="checkbox" name="checkbox2" id="checkbox2"> <label for="checkbox2">Checkbox</label></div>
    <div class="radio"><input type="checkbox" name="checkbox3" id="checkbox3"> <label for="checkbox3">Checkbox</label></div>
    <div class="radio"><input type="checkbox" name="checkbox4" id="checkbox4"> <label for="checkbox4">Checkbox</label></div>
    <div class="radio"><input type="checkbox" name="checkbox5" id="checkbox5"> <label for="checkbox5">Checkbox</label></div>
    <div class="radio"><input type="checkbox" name="checkbox6" id="checkbox6"> <label for="checkbox6">Checkbox</label></div>
    <div class="radio"><input type="checkbox" name="checkbox7" id="checkbox7"> <label for="checkbox7">Checkbox</label></div>
    <div class="radio"><input type="checkbox" name="checkbox8" id="checkbox8"> <label for="checkbox8">Checkbox</label></div>
    <div class="radio"><input type="checkbox" name="checkbox9" id="checkbox9"> <label for="checkbox9">Checkbox</label></div>
    <div class="radio"><input type="checkbox" name="checkbox10" id="checkbox10"> <label for="checkbox10">Checkbox</label></div>

Thank You!

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