如何在PHP中的标签a上添加onclick事件？

I have a sample code:

$link = '<a href="http://test.com/t123#readmore" class="">Read more</a>';

And my code php add onlick event

$link = preg_replace( '#<a(.+?)href="(.+?)"(.+?)(</a>)#s', '<a href="$2" onclick="test();"></a>', $link);

But error can't add onclick on tag a, how to fix it ?

<a href="http://test.com/t123#readmore" onclick="test();" class="">Read more</a>

Looks pretty good to me... you're missing Read More though... add your third match into your preg_replace statement:

$link = preg_replace( '#<a(.+?)href="(.+?)"(.+?)(</a>)#s', '<a href="$2" onclick="test();">$3</a>', $link);
// <a href="http://test.com/t123#readmore" onclick="test();"> class="">Read more</a>

Demo: https://eval.in/66235

I don't recommend using a regex to do this. If you're going to do this, do it with Javascript and jQuery instead

<script>
$(document).ready(function() {
    $('#testa').click(function() { test(); });
});
</script>
<a href="http://test.com/t123#readmore" onclick="test();" class="" id="testa">Read more</a>