How can I revoke an object URL only after it's downloaded?

问题

I'm saving a file in JavaScript using the following code:

var a = document.createElement('a');
a.href = URL.createObjectURL(new Blob(['SOME DATA']));
a.download = 'some.dat';
a.click();

I want to revoke the URL (using URL.revokeObjectURL) once the file is downloaded. When is it safe to do so?

Can I revoke it immediately after calling a.click() (which seems to work, but I'm not sure it's safe)? In a's click event listener? Is there a way to make a click event listener run after the default action?

回答1:

a.click() on a DOM element simulates a click on the element, instead of propagation of the click event, so it's directly sent to the browser. I believe it would be a little bit safer to move revoking of URL object to another event cycle using a timer:

setTimeout(function() {
 URL.revokeObjectURL(a.href);
}, 0);

来源：https://stackoverflow.com/questions/37240551/how-can-i-revoke-an-object-url-only-after-its-downloaded