How to export source content within div to text/html file

You could use something like this:

Updated jsfiddle with download btn(jquery)

Initial jsfiddle with plain js and autoexecution

html

<div id="main">
    <span>Hey there</span>
</div>

html – Edit (Added a link to perform this action)

<a href="#" id="downloadLink">Download the inner html</a>

Js

function downloadInnerHtml(filename, elId, mimeType) {
    var elHtml = document.getElementById(elId).innerHTML;
    var link = document.createElement('a');
    mimeType = mimeType || 'text/plain';

    link.setAttribute('download', filename);
    link.setAttribute('href', 'data:' + mimeType  +  ';charset=utf-8,' + encodeURIComponent(elHtml));
    link.click(); 
}

var fileName="tags.html"; // You can use the .txt extension if you want

JS – Edit

Since you said in the comments that you are using jQuery i’ll call this function from a handler, instead of calling it directly.

$('#downloadLink').click(function(){
    downloadInnerHtml(fileName, 'main','text/html');
});

You can download as a text, just remove the third argument for function, and it will take the default which is “text/plain”, and add the extension .txt to the filename instead of html.

Note
I edited this answer since the person who asked commented that he was looking how to make it work with a handler, he made it work, but just in case.
The original code is in the jsfiddle