In my opinion it is not necessary to use jQuery or XHR to do this, as you can load the files as Resources in the html header.
This way load the files into your HTML header:
<script src="about.txt"></script>
<script src="main.txt"></script>
<script src="more.txt"></script>
In the body of these files declare the content as a variable:
about.txt
var about = '<div class=about> </div>';
main.txt
var main = '<div class=main> </div>';
more.txt
var more = '<div class=more> </div>';
And then when loading the page, the resources you uploaded as text files will be available at variable level to use them, so you can manipulate them at will.
Example (after including files):
console.log(main+about+more);
document.body.innerHTML = main+about+more;
This resolution is perfect thank you very much!
– Hector Gabriel Garcia
Nothing kkkkk, nothing kkkk
– Sampaio Leal
@Hectorgabrielgarcia mark the answer as resolved so that your question can help other users.
– Wendell