Typescript ESType definition improvements

[wesleyolis]

Hi,

The following types can be improved on to be more correct in the lib.es5.d.ts file.

These type improve typically deal with the cases on of the arrays items keys has subset of the other keys, in this case the results is the common subset, with mismatching fields made optional.

This requires functionality in typelevel-ts, however, that is only based on keys.
new methods should do and K in keyof T, T[K] extends S[K] ? K : never

// Improved more correctly helper method.
type ObjectOmit<T extends Record<string,any>, O extends Record<string,any>, KeyOfO keyof O> = Pick<T, {
 [K in keyof T] : K extends KeyOfO ? 
                         T[K] extends O[K] | undefined ? never : K // may need a two way extends comparison here.
                          : K
}[keyof T]

export function ObjectAssign<T extends Record<string,any>, U extends Record<string,any>>(target: T, source: U): 
ObjectOverwrite<T, U>
{
  return Object.assign(target, source);
}

export function ArrayConcat<A>(arrayA: A [] , arrayB : A []) : A[]

export function ArrayConcat<B, A extends B>(arrayA: A [], arrayB : B []) : B & Partial<ObjectOmit<A, keyof B>>[]
export function ArrayConcat<A, B extends A>(arrayA: A [], arrayB : B []) : A & Partial<ObjectOmit<B, keyof A>>[]
{
  return arrayA.concat(arrayB) as any
}


export function FilterDefined<T>(items : Array<T> | undefined) : NonNullable<T> []
{
  if (items)
    return items.filter(f => f != undefined) as NonNullable<T> [];
  else
    return []; 
}

[weswigham]

If someone can open a PR with the suggested change (addition?) on https://github.com/Microsoft/TSJS-lib-generator we can take a look at it and decide if it'll work without breaking the community.

[saschanaz]

If someone can open a PR with the suggested change (addition?) on https://github.com/Microsoft/TSJS-lib-generator

But ES types are not covered by that repo?

[weswigham]

Ahhhh, you would be correct. I suppose here, then.