问题
This error occurred while calling up JSON. I don't know why this error is happening.
$.getJSON(url, function(data){
console.log(data);
});
Error:
Access to XMLHttpRequest at (this is JSON URL) from origin 'null' has been blocked by CORS policy: Cross origin requests are only supported for protocol schemes: http, data, chrome, chrome-extension, https.
回答1:
The error message says it all. You are apparently accessing the page running this script with a protocol scheme other than the several supported for cross-origin requests. This would happen commonly if you are, say, executing a local file in your browser via the file:// protocol and trying to access some URL on the Internet in your $.getJSON call.
来源：https://stackoverflow.com/questions/55252192/from-origin-null-has-been-blocked-by-cors-policy-cross-origin-requests