javascript

CHAPTER 3 ■ OPERATORS
on my part. JavaScript never wastes time and memory doing that. Moreover, if you compare an array to a
function, === does not return false (or !== true) because of those being different subtypes. Rather, the
boolean verdict simply derives from the array and function being in different locations in memory.
Remember, JavaScript stores string, number, boolean, undefined, and null values in a different way to
object, array, and function values (as we inferred earlier in the chapter).
Now don’t be rolling your eyes at me. It’s vital to get this point. So, let’s compare some of the
identical arrays in the following dough object representing the recipe for another of my favorite scones,
hazelnut cherry, with === and !== like so in Firebug. As Figure 3–11 displays, === returns false and !==
returns true for separate but identical arrays.
var dough = {
pastryFlour: [1 + 2/3, "cup"],
hazelnutFlour: [1/3, "cup"],
butter: [3, "tbs"],
sugar: [2, "tbs"],
seaSalt: [1/4, "tsp"],
soda: [1/2, "tsp"],
tartar: [1, "tsp"],
heavyWhippingCream: [1, "cup"],
currants: [1/3, "cup"]
};
dough.pastryFlour === [1 + 2/3, "cup"];
// false
dough.currants !== [1/3, "cup"];
// true
Figure 3–11. Separate but identical arrays are not equal.
Separate but identical values of the object type or array and function subtypes are never equal. Like
you and me, those are equal only to themselves, as the following sample and Figure 3–12 display:
var dough = {
pastryFlour: [1 + 2/3, "cup"],
hazelnutFlour: [1/3, "cup"],
butter: [3, "tbs"],
sugar: [2, "tbs"],
seaSalt: [1/4, "tsp"],
soda: [1/2, "tsp"],
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