CodeParkfunction count(items: string[] | null) {
if (typeof items === "object") {
return items.length;
}
return 0;
}
No:
items is possibly null, because typeof null is also "object"No, it does not compile: items is possibly null. In JavaScript, typeof null is "object". TypeScript models this, so the check narrows items to string[] | null, not to string[].
The option "Yes: the typeof check narrows items to string[]" is the tempting wrong answer for this reason. Use if (items) or items !== null instead.
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