ethers.js/packages/providers/src.ts/browser-ws.ts

"use strict";

import { Logger } from "@ethersproject/logger";
import { version } from "./_version";

let WS: any = null;

try {
    WS = (WebSocket as any);
    if (WS == null) { throw new Error("inject please"); }
} catch (error) {
    const logger = new Logger(version);
    WS = function() {
        logger.throwError("WebSockets not supported in this environment", Logger.errors.UNSUPPORTED_OPERATION, {
            operation: "new WebSocket()"
        });
    }
}

module.exports = WS;