<p>
Will Mateson<br />
Box 61<br />
Cleveland, Ohio<br />
</p>
//setting this css style solving problem with new line in textContent
h1.setAttribute('style', 'white-space: pre;');
//add
in text everywhere You want for line-break (new line)
h1.textContent = "this is line one
and this is line 2";
white-space: pre-line;