The “‘Sys’ is undefined” error in JavaScript typically occurs when the script is trying to access an object or variable named “Sys” that has not been defined or is not in the current scope. This error usually indicates that there is a problem with the code or with the way the script is being loaded.
Here are some common causes of this error:
- The script that is trying to access ‘Sys’ is loaded before the script that defines it.
- The script that defines ‘Sys’ is not loaded at all.
- The script that defines ‘Sys’ is loaded but it has some errors that prevent it from working correctly.
- There is a typo in the name of the object or variable.
To fix this error, you will need to check the following:
- Make sure that the script that defines ‘Sys’ is loaded before the script that is trying to access it.
- Make sure that the script that defines ‘Sys’ is not loaded multiple times.
- Check the script that defines ‘Sys’ for any errors, like syntax errors or missing dependencies.
- Check the spelling of the object or variable in the code.
It’s also helpful to check the browser’s developer tools to see if there are any console errors related to ‘Sys’ and the script that defines it.
You can also check the network tab and check if the script file is being loaded properly or if there is any 404 error.
It could also be that Sys is part of a framework or a library, in that case, you should check if it’s properly installed and loaded.