Relationship of two different JavaScript files?

Remember that Javascript that you are shown on the page is being loaded via the <script> tags in html. So what is essentially happening when you put in the <script src = "***.js"></script>, you are calling in the code that you wrote into html. You can essential make the code work exactly the same way by copying the stuff that you wrote in javascript syntax and then pasting it between the <script></script>.

In the project, you have student.js and student_report.js, which are then loaded into html using the above method. At this point, the two different js codes will exist together in the same space, and will be able to recognize the variables declared on another js file.

However, there is a catch to this as well. Dave explains that the student_report.js file needs to be loaded after the student.js file because it is dependent on the student.js file. This is because when the code is loaded via <script> tag, the code will run. Since student_report.js will call on a variable declared in student.js, if student_report.js is run before student.js, it will see that the variable that it was looking for has not been declared yet and just spit out an error.

Now, on the question of "what would happen if you had multiple js files with the variable that use the same name loaded in". This basically follows a similar logic as above. If multiple js files are called in, they will be loaded on the order that is given on the html from top to bottom. As we know, the value of a variable, if declared multiple time, will end up with the very last value you give it. So, the value of the variable of the same name will end up with the value that it was assigned to on the very last js file that was called containing that variable.