如何将字符串数组“变量”转换为打字稿类型？

Question

I'd like to know how to convert array of string variable to type script types.

Note: There are two SO answers already that deal with this but strings are passed hardcoded to keep values of strings as they are.

• How to convert array of strings to typescript types?
• Convert array of strings to TypeScript type

Both answers pass an array in-line to keep string values in array as literals. But when you pass an array as a variable, it fails to work.

Passing values in-line works.

But passing values as a variable doesn't work

Question

So how do you create a type to limit a list of allowable string values in domElements as a variable to asLiterals ?

Answer 1

When an array literal is assigned to a variable, it is widened to match the typical behavior.

Because of that, the variable domElements is of type string[] instead of ('a' | 'div' | ...)[]

The answer is in your own code. Use a similar function as your asLiterals() to create a literal array.

export function literalArray<T extends KeyTypes>(...entries: T[]): T[] {
    return entries
}

You can also find this function in the type-plus library.