Traffic light — visuco

Challenge 7 of 20

The red and green lights are placed already, and the amber goes exactly between them, which is the middle of the window. Reading the two lines you have is quicker than working it out.

Write the line for the amber light.

Your code JavaScript

Write the line for the amber light.

Console print() output

0 / 30 frames · 400×400

Target

Yours

Results

Press Run to check your code

Penalties: none this run

Report this challenge

Lesson Put It All Together

Everything from this course in one place: number variables, words, the four sums, and placing shapes with width and height.

As in the last topic of Course 1, each picture has missing lines with a // comment above telling you what to write. The difference is that positions should now be worked out from variables rather than typed as fixed numbers. If a comment says "60 left of the middle", that is width / 2 - 60, not 140.

It gives the same answer today, but it says why. Written that way the picture still holds together if a number above it changes, and it reads as a description of the drawing rather than a list of measurements someone once took. That is the habit worth building.

Two things make these easier than they look. Most pictures are symmetrical, so a line you have already written is usually most of the next one — copy it and change the number that differs. And where a value is already sitting in a box, use its name rather than the number inside it.

Take the lines one at a time and press Run after each. A picture that is half right scores partly right, so you can watch yourself getting closer rather than guessing at the end.