javascript

Figure 4–11. Rummaging through the spices array with a do while loop
CHAPTER 4 ■ CONTROLLING FLOW
Here, === will compare "cinnamon" to "lemon peel" no matter what, since JavaScript always takes at
least one roundabout of a do while loop. Thereafter, JavaScript will do another iteration only if i <
spices.length returns true. Since spices.length evaluates to 15, JavaScript will run the do while path 15
times unless we tell it otherwise with a break statement, which we do in the event we find "lemon peel"
in spices. Finally, our loop variable i contains the index by which we query elements in spices, so we
increment i with the ++ operator at the end of the path. In this way, JavaScript can decide whether there
is any point to taking another roundabout.
In the event that JavaScript finds "lemon peel" while rummaging through spices, it assigns false to
putTheKaiboshOn. This variable in turn enables JavaScript to decide whether our recipe is doable. If
putTheKaiboshOn is false, JavaScript prints "Go right ahead!". Otherwise, it prints "No can do!". Test
that your code works both ways by running the sample with and without "lemon peel" in the spices
array.
Before moving on, let’s rework our do while loop as a while loop. Doing so illustrates that JavaScript
unconditionally takes the first roundabout of a do while loop and then conditionally takes any
subsequent ones. Therefore, to emulate such behavior with a while loop, you would have to key in the
path twice like so:
path
while (expression) path
With this in mind, click Clear in both Firebug panels, and let’s try to pull this off:
var spices = [
"cinnamon",
"ginger",
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