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<html><head><script src="https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script><script>$(document).ready(function(){ $("button").click(function(){ $("<span><b>Hello world!</b></span>").replaceAll("p:last-child"); });});</script></head><body><button>Replace every p element that is the last child of its parent, with a bold span element</button><br><br><div style="border:1px solid"> <p>The first paragraph in div.</p> <p>The last paragraph in the div.</p></div><br><div style="border:1px solid"> <p>The first paragraph in another div.</p> <p>The last paragraph in another div.</p></div></body></html>