engine.io-parser/build/esm/decodePacket.js

import { ERROR_PACKET, PACKET_TYPES_REVERSE, } from "./commons.js";
export const decodePacket = (encodedPacket, binaryType) => {
    if (typeof encodedPacket !== "string") {
        return {
            type: "message",
            data: mapBinary(encodedPacket, binaryType),
        };
    }
    const type = encodedPacket.charAt(0);
    if (type === "b") {
        const buffer = Buffer.from(encodedPacket.substring(1), "base64");
        return {
            type: "message",
            data: mapBinary(buffer, binaryType),
        };
    }
    if (!PACKET_TYPES_REVERSE[type]) {
        return ERROR_PACKET;
    }
    return encodedPacket.length > 1
        ? {
            type: PACKET_TYPES_REVERSE[type],
            data: encodedPacket.substring(1),
        }
        : {
            type: PACKET_TYPES_REVERSE[type],
        };
};
const mapBinary = (data, binaryType) => {
    switch (binaryType) {
        case "arraybuffer":
            if (data instanceof ArrayBuffer) {
                // from WebSocket & binaryType "arraybuffer"
                return data;
            }
            else if (Buffer.isBuffer(data)) {
                // from HTTP long-polling
                return data.buffer.slice(data.byteOffset, data.byteOffset + data.byteLength);
            }
            else {
                // from WebTransport (Uint8Array)
                return data.buffer;
            }
        case "nodebuffer":
        default:
            if (Buffer.isBuffer(data)) {
                // from HTTP long-polling or WebSocket & binaryType "nodebuffer" (default)
                return data;
            }
            else {
                // from WebTransport (Uint8Array)
                return Buffer.from(data);
            }
    }
};