JavaScript multiline search for string in string with delimiters or markers. Uses regex

regex-search.js

var start = "some starting term";
var end = "some ending term";
var reg = new RegExp("(?:"+ start +")([\\s\\S]*)(?:"+ end +")", "igm");
var j = res.match( reg );

// example with search markers
var txt = `Lorem Ipsum is simply dummy
text of the printing and typesetting industry.
Lorem Ipsum has been the industry's standard
dummy text ever since the 1500s, when an unknown printer
took a galley of type and scrambled it to make
a type specimen book.`;
var start = 'Ipsum'
var end = 'dummy'
var reg = new RegExp("(?:"+ start +")([\\s\\S]*)(?:"+ end +")", "igm");
var j = txt.match( reg );
console.log(j) 
// ["Ipsum is simply dummy ↵text of the printing and ty…rem Ipsum has been the industry's standard ↵dummy"]