Easiest way to open a download window without navigating away from the page

What is the best cross browser way to open a download dialog (let's assume we can set content-disposion:attachment in the headers) without navigating away from the current page, or opening popups, which doesn't work well in Internet Explorer(IE) 6.

This javascript is nice that it doesn't open a new window or tab.

window.location.assign(url);

7 years have passed and I don't know whether it works for IE6 or not, but this prompts OpenFileDialog in FF and Chrome.

var file_path = 'host/path/file.ext';
var a = document.createElement('A');
a.href = file_path;
a.download = file_path.substr(file_path.lastIndexOf('/') + 1);
document.body.appendChild(a);
a.click();
document.body.removeChild(a);

I know the question was asked 7 years and 9 months ago but many posted solutions doesn't seem to work, for example using an <iframe> works only with FireFox and doesn't work with Chrome.

Best solution:

The best working solution to open a file download pop-up in JavaScript is to use a HTML link element, with no need to append the link element to the document.body as stated in other answers.

You can use the following function:

function downloadFile(filePath){
    var link=document.createElement('a');
    link.href = filePath;
    link.download = filePath.substr(filePath.lastIndexOf('/') + 1);
    link.click();
}

In my application, I am using it this way:

downloadFile('report/xls/myCustomReport.xlsx');

Working Demo:

function downloadFile(filePath) {
  var link = document.createElement('a');
  link.href = filePath;
  link.download = filePath.substr(filePath.lastIndexOf('/') + 1);
  link.click();
}

downloadFile("http://www.adobe.com/content/dam/Adobe/en/accessibility/pdfs/accessing-pdf-sr.pdf");

Note:

• You have to use the link.download attribute so the browser doesn't open the file in a new tab and fires the download pop-up.
• This was tested with several file types (docx, xlsx, png, pdf, ...).

I always add a target="_blank" to the download link. This will open a new window, but as soon as the user clicks save, the new window is closed.