extract.js

/**
 * Extract and data from the DOM in JSON format.
 * @param selector {string} - Selector to query.
 * @param extractor {function} - Operation to apply to each DOM element.
 * @param filename {string}
 */
function selectorToJson(selector, extractor, filename) {
    const elements = document.querySelectorAll(selector);
    const data = Array.from(elements).map(extractor);
    if(filename == null) {
        return data;
    }
    const blob = new Blob([JSON.stringify(data)], {type: 'text/json'});
    const a = document.createElement('a');
    a.download = filename;
    a.href = window.URL.createObjectURL(blob);
    a.dataset.downloadurl =  ['text/json', a.download, a.href].join(':');
    const evt = new MouseEvent('click');
    a.dispatchEvent(evt);
}