reactotron-react-native/dist/module/xhr-interceptor.js

A development tool to explore, inspect, and diagnose your React Native apps.

"use strict";

/* eslint-disable prefer-rest-params */

/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * Vendored from: https://github.com/callstackincubator/rozenite/blob/402e3579878f72cbae7f8123f9ca80459dc1fe7f/packages/network-activity-plugin/src/react-native/http/xhr-interceptor.ts
 * Original source: https://github.com/facebook/react-native/blob/2c683c5787dd03ac15d2aad45dcc53650529ee7f/packages/react-native/src/private/devsupport/devmenu/elementinspector/XHRInterceptor.js
 */

const originalXHROpen = XMLHttpRequest.prototype.open;
const originalXHRSend = XMLHttpRequest.prototype.send;
const originalXHRSetRequestHeader = XMLHttpRequest.prototype.setRequestHeader;
let openCallback;
let sendCallback;
let requestHeaderCallback;
let headerReceivedCallback;
let responseCallback;
let isInterceptorEnabled = false;

/**
 * A network interceptor which monkey-patches XMLHttpRequest methods
 * to gather all network requests/responses, in order to show their
 * information in the React Native inspector development tool.
 * This supports interception with XMLHttpRequest API, including Fetch API
 * and any other third party libraries that depend on XMLHttpRequest.
 */
export const XHRInterceptor = {
  /**
   * Invoked before XMLHttpRequest.open(...) is called.
   */
  setOpenCallback(callback) {
    openCallback = callback;
  },
  /**
   * Invoked before XMLHttpRequest.send(...) is called.
   */
  setSendCallback(callback) {
    sendCallback = callback;
  },
  /**
   * Invoked after xhr's readyState becomes xhr.HEADERS_RECEIVED.
   */
  setHeaderReceivedCallback(callback) {
    headerReceivedCallback = callback;
  },
  /**
   * Invoked after xhr's readyState becomes xhr.DONE.
   */
  setResponseCallback(callback) {
    responseCallback = callback;
  },
  /**
   * Invoked before XMLHttpRequest.setRequestHeader(...) is called.
   */
  setRequestHeaderCallback(callback) {
    requestHeaderCallback = callback;
  },
  isInterceptorEnabled() {
    return isInterceptorEnabled;
  },
  enableInterception() {
    if (isInterceptorEnabled) {
      return;
    }
    // Override `open` method for all XHR requests to intercept the request
    // method and url, then pass them through the `openCallback`.
    // $FlowFixMe[cannot-write]
    // $FlowFixMe[missing-this-annot]
    XMLHttpRequest.prototype.open = function (method, url) {
      if (openCallback) {
        openCallback(method, url, this);
      }
      originalXHROpen.apply(this, arguments);
    };

    // Override `setRequestHeader` method for all XHR requests to intercept
    // the request headers, then pass them through the `requestHeaderCallback`.
    // $FlowFixMe[cannot-write]
    // $FlowFixMe[missing-this-annot]
    XMLHttpRequest.prototype.setRequestHeader = function (header, value) {
      if (requestHeaderCallback) {
        requestHeaderCallback(header, value, this);
      }
      originalXHRSetRequestHeader.apply(this, arguments);
    };

    // Override `send` method of all XHR requests to intercept the data sent,
    // register listeners to intercept the response, and invoke the callbacks.
    // $FlowFixMe[cannot-write]
    // $FlowFixMe[missing-this-annot]
    XMLHttpRequest.prototype.send = function (data) {
      if (sendCallback) {
        sendCallback(data, this);
      }
      if (this.addEventListener) {
        this.addEventListener("readystatechange", () => {
          if (!isInterceptorEnabled) {
            return;
          }
          if (this.readyState === this.HEADERS_RECEIVED) {
            const contentTypeString = this.getResponseHeader("Content-Type");
            const contentLengthString = this.getResponseHeader("Content-Length");
            let responseContentType, responseSize;
            if (contentTypeString) {
              responseContentType = contentTypeString.split(";")[0];
            }
            if (contentLengthString) {
              responseSize = parseInt(contentLengthString, 10);
            }
            if (headerReceivedCallback) {
              headerReceivedCallback(responseContentType, responseSize, this.getAllResponseHeaders(), this);
            }
          }
          if (this.readyState === this.DONE) {
            if (responseCallback) {
              responseCallback(this.status, this.timeout, this.response, this.responseURL, this.responseType, this);
            }
          }
        }, false);
      }
      originalXHRSend.apply(this, arguments);
    };
    isInterceptorEnabled = true;
  },
  // Unpatch XMLHttpRequest methods and remove the callbacks.
  disableInterception() {
    if (!isInterceptorEnabled) {
      return;
    }
    isInterceptorEnabled = false;
    // $FlowFixMe[cannot-write]
    XMLHttpRequest.prototype.send = originalXHRSend;
    // $FlowFixMe[cannot-write]
    XMLHttpRequest.prototype.open = originalXHROpen;
    // $FlowFixMe[cannot-write]
    XMLHttpRequest.prototype.setRequestHeader = originalXHRSetRequestHeader;
    responseCallback = null;
    openCallback = null;
    sendCallback = null;
    headerReceivedCallback = null;
    requestHeaderCallback = null;
  }
};
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