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 ...

Then, add images and photos to the page ... As you continue to learn HTML, CSS and JavaScript, embrace a growth mindset. With practice and experimentation, you’ll gain confidence and develop ...

in that while it parses and renders HTML and CSS with JPEG and PNG image support, it does so only with a subset of HTML and is not tolerant of any malformations. There is also no JS support ...