I'm Kinda new to TypeScript and was wondering what is the difference between,
let array: SomeClass[]; and
let array: [SomeClass];?
What does the different positions of the brackets mean?
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Does this answer your question? Difference between type[] and [type] in TypeScriptJo Liss– Jo Liss2024-03-22 17:40:06 +00:00Commented Mar 22, 2024 at 17:40
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2 Answers
The answer is to do with the amount of instances in each array
someClass[] will mean an array with an infinate length of that class
[someClass] will mean a tuple with a length of one of that class
Ie
someClass[] can be: [someClass], [someClass, someClass] or [someClass, someClass, someClass, someClass] with any amount of values
Whereas [someClass] can only be: [someClass] and no other amount of values in the array
Comments
let array: [SomeClass]; defines an array with exaclty one value while let array: SomeClass[]; defines an array with an undefined number of items
4 Comments
Vincent Menzel
A tuple type is another sort of Array type that knows exactly how many elements it contains, and exactly which types it contains at specific positions. Its the same thing. The a tuple by Definition just knows the amount of values in an array. So an array that always has one entry is a tuple and the other way around. JS dosn't support true tupels so every tupel in JS is an array
VLAZ
A tuple is a different concept entirely. It's a TypeScript happens to realise it through arrays but that doesn't mean an array and duple are the same thing outside of TS.
Vincent Menzel
Yes but as I said JS does not support Tupels only arrays.