If you have a quick idea in mind that you want to implement or a simple code to test and you do not want to install any development environment. You can quickly use one of the online integrated development environments. They provide you with an online interface that supports many different programming languages where you can directly type your code, compile, and run it.
Here are some of the top online IDEs:
https://codepen.io/ (for front end developers)
and finally, this very rich list provided by tutorials point: https://www.tutorialspoint.com/codingground.htm