jquery 全选全不选反选

1.概述
在项目中经常遇到列表中对复选框进行勾选操作，全选。。。反选。。
2. example
<html>
<body>
<form id="test-form" action="test">
    <legend>请选择想要学习的编程语言：</legend>
    <fieldset>
        <p><label class="selectAll"><input type="checkbox"> <span class="selectAll">全选</span><span class="deselectAll">全不选</span></label> <a href="#0" class="invertSelect">反选</a></p>
        <p><label><input type="checkbox" name="lang" value="javascript"> JavaScript</label></p>
        <p><label><input type="checkbox" name="lang" value="python"> Python</label></p>
        <p><label><input type="checkbox" name="lang" value="ruby"> Ruby</label></p>
        <p><label><input type="checkbox" name="lang" value="haskell"> Haskell</label></p>
        <p><label><input type="checkbox" name="lang" value="scheme"> Scheme</label></p>
        <p><button type="submit">Submit</button></p>
    </fieldset>
</form>
<script src="jquery-3.1.0.js"></script>
<script type="text/javascript">
$(function(){
  (function(){
    var
        form = $('#test-form'),
        langs = form.find('[name=lang]'),
        selectAll = form.find('label.selectAll :checkbox'),
        selectAllLabel = form.find('label.selectAll span.selectAll'),
        deselectAllLabel = form.find('label.selectAll span.deselectAll'),
        invertSelect = form.find('a.invertSelect');

        // 重置初始化状态:
        form.find('*').show().off();
        form.find(':checkbox').prop('checked', false).off();
        deselectAllLabel.hide();
        // 拦截form提交事件:
        form.off().submit(function (e) {
            e.preventDefault();
            alert(form.serialize());
        });
  
  var count = 1;   //点击全选/全不选框次数
    selectAll.click(function(){
        if(count++ %2){
             selectAllLabel.hide();
             deselectAllLabel.show();
             $(this).prop("checked", false);
             langs.prop("checked", true);
        }else {
             selectAllLabel.show();
             deselectAllLabel.hide();
             $(this).prop("checked", false);
             langs.prop("checked", false);
        }
    });
    invertSelect.on('click', function(){
        langs.map(function(){
             $(this).prop('checked', !this.checked);
        });
    });
  
  })();
});

</script>

</body>
</html>
jquery 全选 全不选 反选

jquery 全选全不选反选
