What Is Just-In-Time Compiler (JIT Compiler)?

When you think of a compiler, you probably picture a guy in a lab coat with a pocket protector, hunched over a terminal. He's working on that big, thick book of instructions for the computer. This is the traditional way we think about compilers—they compile code ahead of time, and then the computer runs it. But what if there was another way? What if you could compile code as you needed it? Well, there is! Meet the just-in-time (JIT) compiler. It compiles code during program execution, not ahead of time. The traditional compiler may have been bulky and slow at compiling code, but this new breed of a leaner compiler can do it on the fly as your program runs! You can take advantage of this speed by using JIT technology to automatically compile code when needed—instead of waiting for it to be done before running it. This will make your programs run faster and more efficiently than ever before! The difference between an ahead-of-time (AOT) compiler and a just-in-time (JIT) compiler is the difference between a cupcake and a soufflé. The first is ready to go before you even put it in your mouth. A cupcake is baked, frosted, and prepared to serve. You can eat it right away or save it for later—no matter when you eat it. It's going to taste delicious. A soufflé doesn't get cooked until you put it in the oven—it doesn't have any flavor until you put some heat on it! The second is more like an omelette. Omelets are made from scratch as they cook—they're not entirely done until they're served. And when you make an omelet at home? Well… maybe you add some cheese, ham, spinach, or something else that's hot at that moment. But when someone else makes your omelet? They might add something different… like mushrooms or bacon or tomatoes depending on what they had in their fridge! JIT compilers are like omelets—they're cooking as they run because they don't have all their code compiled ahead of