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63 lines
1.9 KiB
JavaScript

import { ERROR_PACKET, PACKET_TYPES_REVERSE, } from "./commons.js";
import { decode } from "./contrib/base64-arraybuffer.js";
const withNativeArrayBuffer = typeof ArrayBuffer === "function";
export const decodePacket = (encodedPacket, binaryType) => {
if (typeof encodedPacket !== "string") {
return {
type: "message",
data: mapBinary(encodedPacket, binaryType),
};
}
const type = encodedPacket.charAt(0);
if (type === "b") {
return {
type: "message",
data: decodeBase64Packet(encodedPacket.substring(1), binaryType),
};
}
const packetType = PACKET_TYPES_REVERSE[type];
if (!packetType) {
return ERROR_PACKET;
}
return encodedPacket.length > 1
? {
type: PACKET_TYPES_REVERSE[type],
data: encodedPacket.substring(1),
}
: {
type: PACKET_TYPES_REVERSE[type],
};
};
const decodeBase64Packet = (data, binaryType) => {
if (withNativeArrayBuffer) {
const decoded = decode(data);
return mapBinary(decoded, binaryType);
}
else {
return { base64: true, data }; // fallback for old browsers
}
};
const mapBinary = (data, binaryType) => {
switch (binaryType) {
case "blob":
if (data instanceof Blob) {
// from WebSocket + binaryType "blob"
return data;
}
else {
// from HTTP long-polling or WebTransport
return new Blob([data]);
}
case "arraybuffer":
default:
if (data instanceof ArrayBuffer) {
// from HTTP long-polling (base64) or WebSocket + binaryType "arraybuffer"
return data;
}
else {
// from WebTransport (Uint8Array)
return data.buffer;
}
}
};