What will this print?
function doSomething(iterations = 0) {
if (iterations < 10) {
console.log("Let's do this again!")
doSomething(iterations++)
}
}
doSomething()
The answer is it will print
Let's do this again! Let's do this again! Let's do this again! Let's do this again! Let's do this again! Let's do this again! Let's do this again! Let's do this again! ...forever...
The bug is the use of a "postfix increment" which is a bug I had in some production code (almost, it never shipped).
The solution is simple:
console.log("Let's do this again!")
- doSomething(iterations++)
+ doSomething(++iterations)
That's called "prefix increment" which means it not only changes the variable but returns what the value became rather than what it was before increment.
The beautiful solution is actually the simplest solution:
console.log("Let's do this again!")
- doSomething(iterations++)
+ doSomething(iterations + 1)
Now, you don't even mutate the value of the iterations variable but create a new one for the recursion call.
All in all, pretty simple mistake but it can easily happen. Particular if you feel inclined to look cool by using the spiffy ++ shorthand because it looks neater or something.
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