Example of how ajax assigns values to global variables

Today, I encountered a problem while working on the project. I use ajax. ajax, the value is not obtained at this time, so the value assignment is unsuccessful. ajax ({assign a value to the global variable. You need to change it to a synchronization operation, that is, add async: false.
Copy codeThe Code is as follows:
$. Ajax ({
Type: "post ",
Url: "a. action ",
Data :{},
DataType: 'text ',
Async: false, // you can assign a value to the global variable after the synchronization operation.
Success: function (data ){
Usersname = data; // usersname is the previously declared global variable
}
});