A snippet to extract all file extension names from wikipedia pages.

extract-file-extensions-from-wikipedia.js

/**
 * This snippet is used to extract all file extension names from wikipedia pages.
 *
 * Usage: Copy this snippet and paste on Chrome console. Do it for each extensions page available.
 * After that, get the json using `localStorage.getItem('extensions')`
 * @see https://en.wikipedia.org/wiki/List_of_filename_extensions
 * @type {string}
 */

var memorySlot='extensions';
var memory = localStorage.getItem(memorySlot);
if (!memory) {
    var data = {};
} else {
    var data = JSON.parse(memory);
}

$('.wikitable tr').each(function (k, v) {
    let tds = $(v).find('td');

    let extension = $(tds[0]).text().toString().replace("\n",'');
    let description = ($(tds[1]).text()).toString().replace("\n",'');

    if (typeof data[extension] == "undefined") {
        data[extension] = {
            'descriptions': []
        };
    }
    data[extension].descriptions.push(description)
});

localStorage.setItem(memorySlot, JSON.stringify(data));

console.log(data);