JavaScript之return false

js中用return false 阻止默认行为
方式1：有效

<div>    <a href="www.baidu.com">sfdhsdh</a></div><script>    var elem=document.querySelector('a');    elem.onclick=function(){return false;}    //或者elem.onclick=abc;    //function abc(){return false;}    //相当于elem.onclick=function(e){e.preventDefault();}</script>

方式2：无效

<div>    <a href="www.baidu.com">sfdhsdh</a></div><script>    var elem=document.querySelector('a');    elem.addEventListener('click', abc, false);    function abc(){return false;}    //function abc(e){e.preventDefault();}有效</script>

方式3：无效

var elem=document.querySelector('a');elem.addEventListener('click', function(){return false;}, false);

方式4：有效

<div>    <a href="www.baidu.com" onclick="return false;">sfdhsdh</a></div>

方式5：无效

<div>    <a href="www.baidu.com" onclick="abc()">sfdhsdh</a></div><script>    function abc(){return false;}</script>

方式6：有效

<div>    <a href="www.baidu.com" onclick="abc();return false;">sfdhsdh</a></div><script>    function abc(){console.log('abc');}</script>

js中return false只能阻止浏览器的默认行为，不能阻止冒泡

<div>    <a href="www.baidu.com" onclick="return false;">sfdhsdh</a></div><script>    var div=document.querySelector('div');    div.addEventListener('click', abc, false);    function abc(e){console.log('aaa');}    //点击链接    //aaa

jquery中return false既能阻止默认事件，又能阻止冒泡

<div>    <a href="www.baidu.com">sfdhsdh</a></div><script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script><script>    $('a').on('click',function(){return false;})    $('div').on('click', abc);        function abc(e){console.log('aaa');}</script>

不会输出‘aaa’