The Browser

When you write Javascript, how does the browser understand what’s been written?

Well, this is handle by a javascript engine and different browsers have different javascript engine

Lets focus on the most popular browser or should i say my favourite browser, Google Chrome.

V8 engine

Google Chrome uses the javascript engine called v8 engine.

“So what’s the purpose of the v8 engine , you may ask ,well the same purpose like any other javascript engine , that is to convert javascript code to binary so that the computer can understand .

Components of the V8 engine

The engine consists of two main components :

Memory Heap — this is where the memory allocation happens

Call Stack — this is to keep track of where we are in the code execution

How do we get to machine code ?

To get to machine code , your javascript file will either have to be compiled or interpeted .

Compilation — the entire source code is converted into machine code at once.

Interpretation — in interpretation , there is an interpreter which runs through the source code and executes it line by line.

Is Javascript compiled or interpreted ?

Javascript used to be a purely interpreted language but the problem with interpreted languages is that they are much, much slower than compiled languages.

Modern Javascript engine now uses a mix between compilation and interpretation which is called just -in-time(JIT) compilation.