Native Javascript, automatically download a BLOB zip file using FETCH without the use of manual triggering clicking a DOM element. Will create a DOM element automatically and set the attribute HREF to a zip file or contents, then download file automatically on HTML file page load. Or also, will work through Node.js or another Fetch compatible Ja…

download_zip.js

/*
 * @Author Raymond Pittman
 * @Github: https://github.com/raymondpittman
 * @Note: Added README.md https://gist.github.com/raymondpittman/11cc82788422d1bddfaa62e60e5ec9aa
 */

/*
 * @params
 * @download: http://.zip
 * @filename: ./downloaded.zip
 */
function download(url, filename) {
    fetch(url, {
        mode: 'no-cors' 
        /*
        * ALTERNATIVE MODE {
        mode: 'cors'
        }
        *
        */
    }).then((transfer) => {
        return transfer.blob();                 // RETURN DATA TRANSFERED AS BLOB
    }).then((bytes) => {
        let elm = document.createElement('a');  // CREATE A LINK ELEMENT IN DOM
        elm.href = URL.createObjectURL(bytes);  // SET LINK ELEMENTS CONTENTS
        elm.setAttribute('download', filename); // SET ELEMENT CREATED 'ATTRIBUTE' TO DOWNLOAD, FILENAME PARAM AUTOMATICALLY
        elm.click()                             // TRIGGER ELEMENT TO DOWNLOAD
    }).catch((error) => {
        console.log(error);                     // OUTPUT ERRORS, SUCH AS CORS WHEN TESTING NON LOCALLY
    })
}
 
/*
 * @CALL
 * EXAMPLE LOCAL FUNCTION CALL
 */
download('http://.zip', 'test.zip');

Unfortunately the updated solution does not work when the file is served without Access-Control-Allow-Origin:* header.

We can use open(), FileSystemObserver, and File System Access API with JSZip to download, extract and write the extracted files and folders to the local filesystem, with the caveat that file permissions are not preserved.

Thank you - you saved my day - was trying for a few hours to get this done.
I needed this in a page showing a spinner and redirect back to the issuing page after the download.
Your code made that possible - Just had to a final then

 .then(() => {
        history.back();
      })