Get tips for instantiating JavaScript's prototype-based objects two ways: via constructor functions or object initialization. Topics Spotlight: New Thinking about Cloud Computing ...

Built-in JavaScript objects and functions are ones you'll use all the time. Here's how to use Object, JSON, String, Math, Date, and console in your JavaScript programs.

The eval method then evaluates that string and returns the actual image object redButton.src. This step gives us the image object that we can then use to replace the currently displayed image.