<p>I have a paragraph, for example: </p> <pre class="brush:html;toolbar:false;"><p> Lorem ipsum <b>amet, consetetur sadipscing elitr, sed diam</b> dolor sit nonumy eirmod tempor Invidunt ut labore et dolore magna aliquyam erat, <i>sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum</i>. Stet clita kasd gubergren, no sea takimata sanctus </p> </pre> <p>There is also a string similar to <code>"Lorem ipsum amet, consetetur sadipscing elitr"</code>. I want to underline this specific string in the original paragraph using Javascript. </p> <p>I think I need to insert a span with a class/ID (-> CSS: text-decoration:underline), but I don't know how to determine the correct index within the paragraph (ignoring any < in a string search ;code><b></code>, <code><i></code>, etc., but including them relative to the span's index). </p> <p>Thanks for any suggestions. </p>

//获取元素的内部内容
var text = document.getElementById("text").innerHTML;

//将要替换的文本用<u>标签包围起来
var newtext = text.replace(/Lorem ipsum <b>amet, consetetur sadipscing elitr/g, "<u>Lorem ipsum <b>amet, consetetur sadipscing elitr</u>");

//将新的下划线文本放回元素中
document.getElementById("text").innerHTML = newtext;

<p id="text">
Lorem ipsum <b>amet, consetetur sadipscing elitr, sed diam</b> dolor sit nonumy eirmod  tempor 
invidunt ut labore et dolore magna aliquyam erat, <i>sed diam voluptua. At vero eos et accusam
et justo duo dolores et ea rebum</i>. Stet clita kasd gubergren, no sea takimata sanctus
</p>