When you make a syntax error in your code, JavaScript will print information about it to the console. Such an error will be displayed in red, and to the right of it the line number, on which this error occurred, will be indicated. This number is a link you can click on, and your code will be opened in the console on the line with the error.
Let's try it in practice. Let's output a non-existent variable. In this case, JavaScript will throw an error:
alert(eee); // Uncaught ReferenceError: eee is not defined
Make a mistake on purpose in your code. Verify that the error appears in the console. Determine the line of code where the error occurred on.