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anonymous123
5,794 PointsJavaScript Interpreter
When I first started learning about JavaScript, I learned how the JavaScript interpreter works. I learned that it reads your code and runs it, simultaneously, but a few days ago I watched a video from this website that says that the JavaScript interpreter reads through the program. It memorizes the functions and checks for any syntax errors. Then it starts to run the program. I looked into this and found a lot of articles from Stanford and other universities that say that the JavaScript interpreter reads your code and runs it, simultaneously, and I read many articles that say the the JavaScript interpreter reads through your code. It memorizes the functions and checks for any syntax errors. Then it starts to run the program. So, does the JavaScript interpreter read your code and run it, simultaneously, or does it read through the program, memorize the functions, check for any syntax errors, and then it starts to run the program?
1 Answer
Michael Hulet
47,913 PointsThis probably isn't the answer you're looking for, but this is irrelevant to you as a JavaScript developer, since this is an implementation detail of the particular interpreter you're using, and might vary between implementations. What these articles are likely talking about is that JavaScript is an interpreted language as opposed to a compiled language like C
Both interpreted and compiled languages ultimately need to translate the code the developer writes into code a computer can read an execute. A compiled language splits this translation and the actual running of the code into 2 separate steps. You translate the code to machine-readable code ahead of time when you're done writing it, and you give your users this executable file that they run. With interpreted languages like JavaScript, you just give your users the code you've written, and they run this code directly. This basically combines the translation and run steps into the same step, and this difference is likely what these articles are pointing out
To answer your question more directly, though, is that since JavaScript allows you to reference symbols that are defined later in the file, it's likely that the interpreter you're using at least tokenizes (reads) all of your code first before actually executing any of it
anonymous123
5,794 Pointsanonymous123
5,794 Pointsthank you so much for the information Michael Hulet