The following simple function allow you to generate a download of a file directly in the browser without contact any server. In this article we are going to show you a couple of tricks to generate and download directly a file using pure Javascript. Therefore, the automatic download of file has been difficult to achieve in the latest years, but now with the introduction of HTML5, this task has become easier to achieve.

However, in the latest browsers unknow or rare downloaded file extensions are blocked and a prompt appears if you really want to open that file (at less in Chrome). To do so, listen to the downloads.onChanged event. Imagine that you use Google Chrome and you have enabled the option 'Auto-open downloaded files', and for your bad luck you enter in a malicious website and it generates the download of an unknown file. If you use URL.createObjectURL () to download data created in JavaScript and you want to revoke the object URL (with revokeObjectURL) later (as it is strongly recommended), you need to do that after the download has been completed. Generate and download a file using Javascript ? If you think about it, this isn't so secure as you think and shouldn't be allowed without the user interaction (however now is allowed).

Javascript download file