# Loops Loops are repetitive conditions where one variable in the loop changes. Loops are handy, if you want to run the same code over and over again, each time with a different value. Instead of writing: ~~~ doThing(cars[0]); doThing(cars[1]); doThing(cars[2]); doThing(cars[3]); doThing(cars[4]); ~~~ You can write: ~~~ for (var i=0; i < cars.length; i++) { doThing(cars[i]); } ~~~