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Exploring Lite-Brite Functionality

Back to our human metaphor: the JavaScript code is the brain and muscle of our webpage! Similar to how the neural and muscular systems are much more complex than the skeleton, the JavaScript work we do will be more complex that our work with HTML and CSS. Please remember: the goal is not for you to be a pro at the end of this, but to get a little bit of exposure!

Understand the Existing Functionality

Click around your Lite-Brite; see if you can “color in” any of the dots. What happens?

Explore to Learn:

On line 2, change black to red. Re-run the program and click a dot.


Now, let’s walk through each line of the existing JavaScript to understand what’s happening:

  • Line 2: A variable called activeColor is set to “black”. This doesn’t mean much yet.
  • Line 5: We accessed the dot-container element from the HTML file, and stored a reference to it in our JavaScipt code. This helps for line 7…
  • Line 7: We told the program to be on the lookout for our user to click anywhere inside the dot-container. If/when that does happen, a function called changeDotColor will run.
  • Line 10: We declare the changeDotColor function
  • Line 12: We ask the program if it was a dot that was actually clicked on (as opposed to the black background in between the dots)
  • Line 14: We change the color of the dot that was clicked on, to the color stored in the activeColor variable.

Here is a marked-up screenshot that illustrates what-is-connected-to-what.

JS Code from Lite-Brite starter kit

Break Code to Learn

That was a LOT of info! Sometimes it soaks in better when we have a chance to poke at the code.

  • On line 5, change dotContainer to container. Run the program (it should no longer work). Now, on line 7, change dotContainer to container and then run the program. It should be back to working!
  • Finally, on line 2, change activeColor to active. Run the program (you guessed it, it should no longer work). Why did things break? What else could you modify at this point to get the functionality back?

Exploring Functionality Summary

  • Like HTML and CSS, JavaScript needs very specific directions
  • Each piece of the puzzle has to be connected to the other (this is why spelling and capitalization can be really important!)

Next Section: Planning & Implementing JavaScript