Some small type-awared utils for TypeScript.

extend_prototype.ts

export { }

declare global {
  interface Array<T> {
    /** Return the last element of this array. */
    last (): T | undefined
    /** Delete the first element from this array. If delete success, return true. */
    delete (elem: T): boolean
    /** Delete the first element satisfying the @param fn. If delete success, return true. */
    deleteIf (fn: (elem: T) => boolean): boolean
  }
}

Array.prototype.last = function () {
  return this[this.length - 1]
}

Array.prototype.delete = function <T> (elem: T): boolean {
  const i = this.indexOf(elem)
  if (i === -1) { return false }
  this.splice(i, 1)
  return true
}

Array.prototype.deleteIf = function <T>(fn: (x: T) => boolean): boolean {
  const i = this.findIndex(fn)
  if (i === -1) { return false }
  this.splice(i, 1)
  return true
}