typescript-devs-cant-stop-me-impl.ts

Object.assign(typeof window === 'object' ? window : typeof global === 'object' ? global : typeof globalThis === 'object' ? globalThis : {}, {
  hasKeys: function<Keys extends string[], Obj extends object>(obj: Obj, keys: Keys): obj is Obj & {
    [key in ValueOf<Keys>]: unknown
  } {
    return keys.every(key => key in obj)
  }
})

typescript-devs-cant-stop-me.d.ts

/**
 * This file augments global types to make more sense and be more practical
 */


/**
 * I think it only makes sense Object.keys() returns an array of keyof object
 */

interface ObjectConstructor {
  keys<T>(obj: T): Array<keyof T>
}

/**
 * I think it only makes sense that you can check any string against an array of string literals
 *
 * Normally, if an array resolves to something like
 *
 * const x: ("rawr" | "mami")[]
 *
 * x.includes("notrawr") will not work
 *
 * That doesn't make sense. bye.
 */

interface Array<T> {
  includes(searchElement: T extends string ? string : T, fromIndex?: number): boolean
}

interface ReadonlyArray<T> {
  includes(searchElement: T extends string ? string : T, fromIndex?: number): boolean;
}

/**
 * You should have a type-safe way of checking if an object has many keys
 */

type ValueOf<T> = T extends any[] ? T[number] : T[keyof T]

function hasKeys<Keys extends string[], Obj extends object>(obj: Obj, keys: Keys): obj is Obj & {
  [key in ValueOf<Keys>]: unknown
}