Document library: add the script editor to Upload.aspx

Open the Upload.aspx page, the gear icon in the right corner of the browser, Edit page, add the web page editor's scripting element and click the Stop editing button. It will work correctly.
In the c-sharpcorner guide, they use the "Default edit form" button on the tape because they do not want to think about what the default form is. The form count can be multiple. Upload page in an instance.