CryptoJS Progressive Ciphering - cryptojs

Question

Is there any other tutorial or documentation on how to do Progressive Ciphering with CryptoJS?
Their own Documentation about it is kinda lacking of Information's
These are the Information's I found:
https://cryptojs.gitbook.io/docs/#progressive-ciphering
https://github.com/brix/crypto-js/blob/develop/docs/QuickStartGuide.wiki

Answer 1

Here's my solution:
export function calcSha1 (file: File): Promise<string> {
const reader = new FileReader()
const promise = new Promise<string>(
(resolve) => {
reader.onloadend = (evt: ProgressEvent<FileReader>) => {
const sha1Hash = CryptoJS.algo.SHA1.create()
let currentPosition = 0
const chunkSize = 10 * 1024 * 1024 // 10MB
while (currentPosition < file.size) {
let endPosition = currentPosition + chunkSize
if (endPosition > file.size) {
endPosition = file.size
}
const blob = evt.target?.result?.slice(currentPosition, endPosition)
const wordArray = CryptoJS.lib.WordArray.create(blob)
sha1Hash.update(wordArray)
currentPosition += chunkSize
}
const result = sha1Hash.finalize()
resolve(result.toString())
}
}
)
reader.readAsArrayBuffer(file)
return promise
}