Check out example codes for "create file object from url typescript". It will help you in understanding the concepts better.

Code Example 1

fetch('//my-image-url')
      .then((e) => {
        return e.blob()
      })
      .then((blob) => {
        let b: any = blob
        b.lastModifiedDate = new Date()
        b.name = ''
        return b as File
      })
// Promise returning a File Object
// (usefull for previewing image in updating forms)

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