What does the action property in the component Element UI — Upload?

Good day! I do not quite understand the purpose of this required attribute. In the example documentation url:

On the LAN and hosting this url responding error (CORS policy), I simply created an empty controller in the project:

module.exports.postAvatar = async (req, res) => {
 try {
Res. json({
 success: true
 } catch (e) {
Res. json({
 success: true,
 message: `Error. ${e.message}`

And the picture began quietly to load in the preview. That's a question, what is the semantic load of the attribute?
April 3rd 20 at 17:37
1 answer
April 3rd 20 at 17:39
This parameter determines where the actual will be sent to the selected file. The component is called "Upload", not "Preview" because the parameter is mandatory.
If you download a file you really don't need, or need special logic - use the parameter in the http request.

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