convert png image to File object in typescript

In my test project I want to convert my png image to Uint8Array. I found some solution

    pngFileToUint8Array(pngPath: string): Promise<Uint8Array> {
    

    const png: File = new File([pngImage], pngPath, { type: 'image/png' });

    return new Promise((resolve, reject) => {
      const reader = new FileReader();

      reader.onload = (event) => {
        const resultArrayBuffer = event.target?.result as ArrayBuffer;
        const uint8Array = new Uint8Array(resultArrayBuffer);
        resolve(uint8Array);
      };

      reader.onerror = (error) => {
        reject(error);
      };

      reader.readAsArrayBuffer(png);
    });
  }

And my problem is how to declare png file to File Object ;/ I have png file on my disk.
Thanks for any tips 🙂