Download file on ajax success node.js

There are basically two popular ways to download a file.

1. Set window.location

Setting window.location to the download url will download the file.

window.location = '/path/to/download?arg=1';

A slightly different version of this is to open a new tab with the download path

window.open('/path/to/download', '_self');

2. Virtual Link Click

With HTML5, you can specify the download attribute of a link. Clicking the link (even programmatically) will trigger a download of the url. The links don't even need to be part of the DOM, you can make them dynamically.

var link = document.createElement('a');
link.href = '/path/to/download';
link.download = 'local_filename.csv';
var e = document.createEvent('MouseEvents');
e.initEvent('click', true, true);
link.dispatchEvent(e);

This isn't supported in all browsers, so even if you want to use this method, you'll have to drop support for some browsers or fallback to the first method.

Luckily, this excellent answer references an awesome little js library that does all this already -- http://pixelscommander.com/polygon/downloadjs/#.VrGw3vkrKHv

downloadFile('/path/to/download');

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2-Step Download

Another convention you'll often see is a two step download, where information is sent to the server at a known url, and the server sends back a generated url or id that can be used to download the file.

This can be useful if you want the url to be something that can be shared, or if you have to pass a lot of parameters to the download generator or just want to do it via a POST request.

$.ajax({
    type: 'POST',
    url: '/download/path/generator',
    data: {'arg': 1, 'params': 'foo'},
    success: function(data, textStatus, request) {
        var download_id = data['id'];
        // Could also use the link-click method.
        window.location = '/path/to/download?id=' + download_id;
    }
});