<html>
<script>
function test()
{
alert('test');
}
</script>
<body onload="test=function(){}"><button onclick="test()">test</button>
</body>
</html>
<script>
function test()
{
alert('test');
}
</script>
<body onload="test=function(){}"><button onclick="test()">test</button>
</body>
</html>
<script>
function test()
{
alert('test');
}
</script>
<body onload="window.tmp=test;test=function(){}"><button onclick="test()">test</button>
<button onclick="test=window.tmp">恢复test的功能</button>
</body>
</html>