in packages/sha1-browser/src/ie11Sha1.ts [11:25]
constructor(secret?: SourceData) {
if (secret) {
this.operation = getKeyPromise(secret).then((keyData) =>
(locateWindow() as MsWindow).msCrypto.subtle.sign(
SHA_1_HMAC_ALGO,
keyData
)
);
this.operation.catch(() => {});
} else {
this.operation = Promise.resolve(
(locateWindow() as MsWindow).msCrypto.subtle.digest("SHA-1")
);
}
}