Auto adds alt text to HTML <img> based upon the filename found in the src. jQuery required.

auto-add-alt-text.js

let fileNameFinder = /([\w\d-]+.jpg|[\w\d-]+.png)/;
let altTextFinder = /(.*)\.[^.]+$/;

$('img').each(function() {

  if(!$(this).attr('alt')) {
    let fileName = $(this).attr('src').match(fileNameFinder)[0];
    let altText = fileName.match(altTextFinder)[1];
    $(this).attr('alt', altText);
  }
});