JSFiddle - React, Tailwind, and code Playground

JavaScript

var html = `<!doctype html>
<html>
<head><title></title></head>
<div id="hi">讀這個</div></html>`; //比如整個是html代碼

get(html,"hi");


function get(html, id) {
    var reA = new RegExp(`<[^<]*id=["']${id}["'].*>([^\<]+)</[^>]*>`,'i');
    
    var mat = html.match(reA);  // 截取內容
    if(mat!==null){
        console.log(mat[1]);
    }
}