I'd like to start by saying that I am doing this series to learn and understand better Typescript, so feel free to correct me or contact me.
Let's create a type for the JavaScript Array.push function. Which takes pushes an element into the array in the last position.
Push<[1, 2], '3'> // [1, 2, '3']
Push<['1', 2, '3'], boolean> // ['1', 2, '3', boolean]
So we know we have an array and our type should return an array + the new value.
type Push<TArray extends unknown[], U> = [...TArray, U]
TArray extends readonly unknown[]
We first check our TArray is of type array.
then we simply spread the array and the new value into an array [...TArray, U]
Thank you!
you can find me here My Twitter
Top comments (0)