夺命雷公狗---在js里阻止a标签的跳转和form表单的跳转

<!DOCTYPE HTML>
<html lang="en-US">
    <head>
        <meta charset="UTF-8">
        <title></title>
    </head>
    <body>
        
        <a href="http://www.baidu.com">百度</a>

        <a href="http://www.qq.com" onclick = "return f1()">腾讯</a>

        <a href="http://www.qq.com" onclick="javascript:return confirm(\'确认要删除吗？\')">删除</a>

        <form action="http://www.taobao.com" method="post" >
            用户名: <input type="text" name="uesrname" />
            <input type="submit" value="提交" />        
        </form>

        <script type="text/javascript">
            function f1(){
                console.log(\'not\');
                return false;
            }
            var a = document.getElementsByTagName(\'a\')[0];
            a.onclick = function(){
                console.log(\'NOT---A\');
                return false;
            }
            
            
            var forms = document.getElementsByTagName(\'form\')[0];
        /* W3C浏览器下的 */
        /*
            forms.addEventListener(\'submit\',function(evt){
                console.log(\'not----form\');
                evt.preventDefault();
            });
        */
        /* IE浏览器下的 */
            forms.attachEvent(\'onsubmit\',function(){
                console.log( \'表单提交了\' );
                window.event.returnValue = false;
            })
            
        </script>
    </body>
</html>