JSFiddle - React, Tailwind, and code Playground

HTML

<div id='result'></div>

JavaScript

var re = new Regex("/<body.*?>(.*?)<\\/body.*?>/","ig"); 

var str = "<html xmlns='http://jabber.org/protocol/xhtml-im'><body lang='en' xmlns='http://www.w3.org/1999/xhtml'>heello</body><body lang='de' xmlns='http://www.w3.org/1999/xhtml'>heello</body></html>"; 

var str2 = "<html xmlns='http://jabber.org/protocol/xhtml-im'><body lang='en' xmlns='http://www.w3.org/1999/xhtml'>heello</body></html>"; 

function match1(regex, string) {
    var matches1 = new Array();
    var matches2 = [10];
    var found;
    while (found = regex.exec(string)) {
        matches1.push(found[0]);
			if (found.length>0)
			{
				matches2.push(found[1]);
			}
        regex.lastIndex = found.index + 1;
    }
    return [matches1,matches2];
};

function parseCode(c) {
    for (var counter = 0; counter < c.length; counter++) {
        result.append((counter + 1) + '.' + ' ' + c[counter]);
        result.append('<br/>');
    }
    result.append('----');
    result.append('<br/>');
};

var res1 = match1(re,str);
parseCode(res1);

var res2 = match1(re,str2);
parseCode(res2);