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Acid Coder
Acid Coder

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Typescript Numeric Literal Types How To X * Y (Multiplication)

#webdev #tutorial #programming #typescript

We have seen how subtraction works

now can we do multiplication?

yes we can, and this is how you do it, method 1:

type CreateArrayWithLengthX< LENGTH extends number, ACC extends unknown[] = [], > = ACC['length'] extends LENGTH ? ACC : CreateArrayWithLengthX<LENGTH, [...ACC,1]> type Multiplication<X extends number, Y extends number, Z extends number[] = []> = [...CreateArrayWithLengthX<Y>]['length'] extends Z['length'] ?[] :[...CreateArrayWithLengthX<X>, ...Multiplication<X,Y,[1,...Z]>] type A = Multiplication<526,19>['length'] // 9994 type B = Multiplication<1,48>['length'] // error if 2nd interger exceed 47
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playground

method 2:

type CreateArrayWithLengthX< LENGTH extends number, ACC extends unknown[] = [], > = ACC['length'] extends LENGTH ? ACC : CreateArrayWithLengthX<LENGTH, [...ACC,1]> type Multiplication<X extends number, Y extends number, Z extends number[] = [], V extends unknown[] = []> = [...CreateArrayWithLengthX<Y>]['length'] extends Z['length'] ? V['length'] : Multiplication<X,Y,[1,...Z],[...CreateArrayWithLengthX<X>,...V]> type A= Multiplication<19,526> // 9994 type B= Multiplication<526,19> // 9994
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limitation: the product cannot exceed 9999 because the max tuple size is 9999

playground

2nd method is better because the 1st method 2nd integer cannot be larger than 47 (method 1 Multiplication is not tail recursion, but still I was expecting it to error at 50, not 48, hmm...)

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