How do browsers execute javascript

Question

I'm trying to figure out if web browsers use an interpreter to execute javascript, or some sort of compiler. It is well known that scripting languages are interpreted not compiled; however there is the JScriptCompiler that can compile javascript into MSIL. This leaves me to wonder if IE, FF, Chrome etc are using some sort of compiler or if it's an interpreter.

Can anyone cite the specific method in which browsers run javascript?

question from:https://stackoverflow.com/questions/5317190/how-do-browsers-execute-javascript

Answer 1

In the past, Javascript was interpreted -- and nothing more.

In the past two years or so, browsers have been implementing new Javascript engines, trying to compile some portions of code, to speed Javascript up.

For more informations on what has been done for Mozilla Firefox, you should take a look at :

• JavaScript:TraceMonkey
• an overview of TraceMonkey

For more informations about Chrome's engine, you'll want to read :

• Dynamic Machine Code Generation

And for webkit (safari) :

• Announcing SquirrelFish

Not sure what has been (or is being) done on other browsers -- but I suppose the same kind of thing exists, or will exist.

And, of course, for more informations : JavaScript engine, on wikipedia.