Download File Using JavaScript/jQuery

Use an invisible <iframe>:

<iframe id="my_iframe" style="display:none;"></iframe><script>function Download(url) {    document.getElementById('my_iframe').src = url;};</script>

To force the browser to download a file it would otherwise be capable of rendering (such as HTML or text files), you need the server to set the file's MIME Type to a nonsensical value, such as application/x-please-download-me or alternatively application/octet-stream, which is used for arbitrary binary data.

If you only want to open it in a new tab, the only way to do this is for the user to a click on a link with its target attribute set to _blank.

In jQuery:

$('a#someID').attr({target: '_blank',                     href  : 'http://localhost/directory/file.pdf'});

Whenever that link is clicked, it will download the file in a new tab/window.

2019 modern browsers update

This is the approach I'd now recommend with a few caveats:

• A relatively modern browser is required
• If the file is expected to be very large you should likely do something similar to the original approach (iframe and cookie) because some of the below operations could likely consume system memory at least as large as the file being downloaded and/or other interesting CPU side effects.

fetch('https://jsonplaceholder.typicode.com/todos/1')  .then(resp => resp.blob())  .then(blob => {    const url = window.URL.createObjectURL(blob);    const a = document.createElement('a');    a.style.display = 'none';    a.href = url;    // the filename you want    a.download = 'todo-1.json';    document.body.appendChild(a);    a.click();    window.URL.revokeObjectURL(url);    alert('your file has downloaded!'); // or you know, something with better UX...  })  .catch(() => alert('oh no!'));