jsFiddle

jsFiddle es una Online Javascript IDE. De la wikipedia Online Javascript IDE:

• An online Javascript IDE (or browser based Javascript IDE, Javascript live coding environment, web playground, javascript sandbox) is an Integrated Development Environment (IDE) that is hosted in a browser, with an aim to ease Javascript, HTML, and CSS based web development.
• Generally, they allow users to edit Javascript code in the browser, and see the results of executing the code. Many will also allow the editing of HTML or CSS content.
• Many of them support saving the work or sharing links with others, leading to their prevalence for showing examples on such sites such as StackOverflow, where a question can be answered by pointing to a working snippet of code.
• Many libraries for Javascript, provide links to demonstration code that can be edited by users.
• They are also used as a pedagogical tool by institutions such as Khan Academy to allow students to experience writing code in an environment where they can see the output of their programs, without needing any setup beyond a web browser.

• Introduction to jsFiddle YouTube
• Documentación de jsFiddle
• Tutorail de jsFiddle