There are many javaScript engines currently available. Different browsers use different javaScript engines. Script performance on browsers depend on the javaScript engine used in the browser.
Some of the most popular javaScript engines are mentioned below.
SpiderMonkey
SpiderMonkey engine is used by Mozilla. This engine is written in C/C++. This engine is used by many of Mozilla products.
Rhino
Rhino is an open-source implementation of javaScript written in Java. This implementation is also used by Mozilla.
Carakan
Carakan is opera’s javascript engine. It is still in development status and opera claims it be faster than the Opera 10 alpha engine.
V8
V8 JavaScript Engine is the google’s javaScript engine. It is written in C++ and is used in Chrome browser.
JavaScriptCore
JavaScriptCore is the javaScript engine used by webkit browsers like safari.
Chakra
Chakra is the javaScript engine used in IE9. This engine is able to produce better performance than in IE8 browser.
Summary:
There are other javaScript engines currently available, but the above ones are being used by today’s browsers. Different browsers use different javaScript rendering engine, hence the execution of javaScript code differs in different browsers.