Drag and drop — arrange the code

Reading code and writing code are different skills — and this lesson drills the one in between: ordering. Each activity shows the lines of a working script shuffled up, with a few imposters mixed in. Tap the right lines in the right order, leave the fakes out, and you've built the script. No typing, just judgment.

#The rule

Code runs top to bottom. So ask yourself at every line: does this need something that only comes later? A variable must be declared before it's used. A function must be defined before it's called. An end must close what a function or if opened.

Let's warm up with a function:

#Order the branches

A conditional checks top to bottom. Decide the order so the right branch wins for a score of 75.

#Count with style

A for loop knows exactly how many laps it runs. Arrange it.

#Listen to the world

Events don't run now — they register for later. Order the connect correctly, passing the function itself, not a call to it.

#The judgment call

You just arranged four scripts — a function, a choice, a loop, and an event. Notice the skill you used: you read a script as a sequence, in your head, and checked every line against the ones around it. That's exactly how you'll read real code when something breaks.