How do browsers execute javascript

Question

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.

Heres' for IE http://blogs.msdn.com/b/ie/archive/2010/03/18/the-new-javascript-engine-in-internet-explorer-9.aspx

And here's FireFox: https://hacks.mozilla.org/2009/07/tracemonkey-overview/

(thanks to Pascal MARTIN)

JScript is a scripting language provided by microsoft. Its compilation is taken care by CLR. Also it can be interpreted. It have tighter integration with Visual studio.

Have a look at http://msdn.microsoft.com/en-us/library/72bd815a%28v=vs.80%29.aspx for detail Jscript description.