This article was originally published on my blog
The solution is to use javascript. For now.
Some of the methods we use here, such as Blob aren't yet implemented in ReasonML (or I just couldn't find them), so we need to put some javascript into our ReasonML code using interop.
Here's a working version using codesandbox you can play with.
https://codesandbox.io/s/how-to-download-arbitrary-data-reasonml-yoxyg
Javascript Interop
In ReasonML, you can wrap javascript with [%bs.raw {| ...code goes here... |}] and it is accessible to the Reason code.
How Downloading works
First, we create a blob (Binary Large OBject) with our text MIME type.
var content = new Blob(["I AM TEXT"], {type: "text/plain"});
Then we create an object url that can reference the data in our Blob and we add this url to the anchor tag.
document.getElementById("download")
.setAttribute("href", window.URL.createObjectURL(content));
Lastly, we set the download attribute so that we can name our downloaded file.
document.getElementById("download")
.setAttribute("download", fileName);
In conclusion, the link to the blob causes the browser to download the file, and gives it our name.
All the code together:
index.html
<html>
<body>
<a href="" id="download">Download File</a>
</body>
</html>
index.re
let setupDownload = [%bs.raw
{|
function() {
var fileName = "data.txt";
var content = new Blob(["I AM TEXT"], {type: "text/plain"});
document.getElementById("download")
.setAttribute("href", window.URL.createObjectURL(content));
document.getElementById("download")
.setAttribute("download", fileName);
}
|}
];
setupDownload();
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