I get the file to a string:
const r = new FileReader()
r.readAsText(file, 'UTF-8')
r.onload = (evt) => {
this.file = evt.target.result
};
After upload a Zip, Text or Image file my string looks like: data:text/plain;base64,VTJGc.....
How can i reverse the readAsText and get a downloadable file?
The "string" you got is a Base64 URL (which you can copy and paste into a new browser tab and view the contents), and it actually simplified downloading the file, so please don't reverse the process.
One way is to create a link element in your HTML and click on it:
The example won't work because it's in an embed that has limited permissions.
function download(b64, name) {
const a = document.createElement("a");
a.href = b64;
a.download = name;
document.body.appendChild(a);
a.click();
}
download("data:text;base64,SGVsbG8sIHdvcmxkIQ==", "helloworld.txt");If you really want to reverse the process, you can easily decode Base64 with atob():
const decode = str =>
atob(str.replace(/^data:\w+;base64,/, "")); // remove `data:text;base64,`
console.log(decode("data:text;base64,SGVsbG8sIHdvcmxkIQ=="));