如何在openresty中hook webworker中的fetch函数？我只能在上游响应的html 代码里操作-Go服务器开发

在 OpenResty 中 Hook WebWorker 的 fetch 函数需要通过修改返回的 HTML/JavaScript 代码来实现，因为 OpenResty 本身无法直接干预浏览器中 WebWorker 的运行环境。以下是具体步骤和示例：

1. 方案思路

目标：拦截 WebWorker 中的 fetch 请求。
限制：OpenResty 只能操作上游返回的 HTML/JS 代码，无法直接修改运行时的 WebWorker 行为。
方法：
1. 注入脚本：在返回的 HTML 中插入一段 JavaScript，覆盖 WebWorker 的 fetch 方法。
2. 劫持通信：通过 postMessage/onmessage 将 WebWorker 的请求转发到主线程，由主线程统一处理。

2. Lua 代码示例（OpenResty）

以下是一个完整的 OpenResty Lua 脚本，用于修改响应内容并注入 Hook 逻辑：

location /your-upstream-path {
    proxy_pass http://your-backend;
    header_filter_by_lua_block {
        -- 仅处理 HTML 响应
        if ngx.header["Content-Type"] and string.find(ngx.header["Content-Type"], "text/html") then
            ngx.header["Content-Length"] = nil -- 清除 Content-Length，因为我们会修改 body
        end
    }
    body_filter_by_lua_block {
        -- Hook WebWorker.fetch() 
        local inject_script = [[
<script>
// Hook WebWorker.fetch() by overriding the Worker's importScripts or constructor
(function() {
    const originalFetch = window.fetch;
    window.fetch = function(...args) {
        console.log("Intercepted fetch in main thread:", args);
        return originalFetch.apply(this, args);
    };

    const originalWorker = window.Worker;
    window.Worker = function(url, options) {
        // Fetch the worker script and modify it to hook fetch()
        const workerScript = originalFetch(url)
            .then(response => response.text())
            .then(text => {
                // Inject our hook into the Worker's code
                const patchedScript = `
                    const originalFetchInWorker = fetch;
                    fetch = function(...args) {
                        console.log("Intercepted fetch in Worker:", args);
                        return originalFetchInWorker.apply(this, args);
                    };
                    ${text}
                `;
                return new Blob([patchedScript], { type: 'application/javascript' });
            })
            .then(blob => URL.createObjectURL(blob));

        return new originalWorker(workerScript, options);
    };
})();
</script>
]]
        
        -- Inject the script before </body>
        local body = ngx.arg[1]
        if body then
            body = string.gsub(body, "</body>", inject_script .. "</body>")
            ngx.arg[1] = body
        end
    }
}

3. Key Points

动态修改 Worker：
- Override window.Worker constructor.
- Fetch the worker script via fetch, modify it to inject our hook, then create a blob URL for the new Worker.
Hook Logic:
- Override fetch in both main thread and worker.
注意事项：
- Requires CORS support if fetching cross-origin worker scripts.
- May break if the worker uses dynamic imports or other advanced features.
Alternative Approach: If you control the worker script, directly modify its source code to include the hook logic instead of patching it dynamically.