file.js

import { Blob } from './index.js'

const _File = class File extends Blob {
  #lastModified = 0
  #name = ''

  /**
   * @param {*[]} fileBits
   * @param {string} fileName
   * @param {{lastModified?: number, type?: string}} options
   */// @ts-ignore
  constructor (fileBits, fileName, options = {}) {
    if (arguments.length < 2) {
      throw new TypeError(`Failed to construct 'File': 2 arguments required, but only ${arguments.length} present.`)
    }
    super(fileBits, options)

    if (options === null) options = {}

    // Simulate WebIDL type casting for NaN value in lastModified option.
    const lastModified = options.lastModified === undefined ? Date.now() : Number(options.lastModified)
    if (!Number.isNaN(lastModified)) {
      this.#lastModified = lastModified
    }

    this.#name = String(fileName)
  }

  get name () {
    return this.#name
  }

  get lastModified () {
    return this.#lastModified
  }

  get [Symbol.toStringTag] () {
    return 'File'
  }

  static [Symbol.hasInstance] (object) {
    return !!object && object instanceof Blob &&
      /^(File)$/.test(object[Symbol.toStringTag])
  }
}

/** @type {typeof globalThis.File} */// @ts-ignore
export const File = _File