JVerstry JVerstry - 4 months ago 11
Javascript Question

How to create a dynamic file + link for download in Javascript?

Typically, HTML pages can have link to documents (PDF, etc...) which can be downloaded from the server.

Assuming a Javascript enabled webpage, is it possible to dynamically create a text document (for example) from within the user browser and add a link to download this document without a round trip to the server (or a minimal one)?

In other word, the user would click on a button, the javascript would generate randoms numbers (for example), and put them in a structure. Then, the javascript (JQuery for example) would add a link to the page to download the result as a text file from the structure.

This objective is to keep all (or at least most) of the workload on the user side.

Is this feasible, if yes how?

Answer

By appending a data URI to the page, you can embed a document within the page that can be downloaded. The data portion of the string can be dynamically concatenated using Javascript. You can choose to format it as a URL encoded string or as base64 encoded. When it is base64 encoded, the browser will download the contents as a file. You will have to add a script or jQuery plugin to do the encoding. Here is an example with static data:

jQuery('body').prepend(jQuery('<a/>').attr('href','data:text/octet-stream;base64,SGVsbG8gV29ybGQh').text('Click to download'))
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