JavaScript blob filename without link
How do you set the name of a blob file in JavaScript when force downloading it through window.location
?
function newFile(data) {
var json = JSON.stringify(data);
var blob = new Blob([json], {type: "octet/stream"});
var url = window.URL.createObjectURL(blob);
window.location.assign(url);
}
Running the above code downloads a file instantly without a page refresh that looks like:
bfefe410-8d9c-4883-86c5-d76c50a24a1d
I want to set the filename as my-download.json instead.
The only way I'm aware of is the trick used by FileSaver.js:
- Create a hidden
<a>
tag. - Set its
href
attribute to the blob's URL. - Set its
download
attribute to the filename. - Click on the
<a>
tag.
Here is a simplified example (jsfiddle):
var saveData = (function () {
var a = document.createElement("a");
document.body.appendChild(a);
a.style = "display: none";
return function (data, fileName) {
var json = JSON.stringify(data),
blob = new Blob([json], {type: "octet/stream"}),
url = window.URL.createObjectURL(blob);
a.href = url;
a.download = fileName;
a.click();
window.URL.revokeObjectURL(url);
};
}());
var data = { x: 42, s: "hello, world", d: new Date() },
fileName = "my-download.json";
saveData(data, fileName);
I wrote this example just to illustrate the idea, in production code use FileSaver.js instead.
Notes
- Older browsers don't support the "download" attribute, since it's part of HTML5.
- Some file formats are considered insecure by the browser and the download fails. Saving JSON files with txt extension works for me.
I just wanted to expand on the accepted answer with support for Internet Explorer (most modern versions, anyways), and to tidy up the code using jQuery:
$(document).ready(function() {
saveFile("Example.txt", "data:attachment/text", "Hello, world.");
});
function saveFile (name, type, data) {
if (data !== null && navigator.msSaveBlob)
return navigator.msSaveBlob(new Blob([data], { type: type }), name);
var a = $("<a style='display: none;'/>");
var url = window.URL.createObjectURL(new Blob([data], {type: type}));
a.attr("href", url);
a.attr("download", name);
$("body").append(a);
a[0].click();
window.URL.revokeObjectURL(url);
a.remove();
}
Here is an example Fiddle. Godspeed.