jsFiddle is the perfect solution; it provides a custom environment (based on user selections) to test (or fiddle with) your JavaScript, HTML, and CSS code right inside your browser. A quick tour ...

Web developers typically have programming skills around HTML, CSS and JavaScript. One of the most popular and common types of web application development is around e-commerce websites ...

The new release brings improvements to JavaScript heap profiles, CSS code formatting ... the semantic highlighting of JavaScript source in HTML files with what is seen in normal .jscode files.