拦截JavaScript中的fetch()API请求和响应 [英] Intercept fetch() API requests and responses in JavaScript

问题描述

我想拦截JavaScript中的提取API请求和响应.

I want to intercept fetch API requests and responses in JavaScript.

例如，在发送请求之前，我要拦截请求URL.我也想在响应到达时就对其进行拦截.

For example, before sending the request I want to intercept the request URL. I'd like to intercept the response once it arrives as well.

以下代码用于拦截所有 XMLHTTPRequest 的响应.

The below code is for intercepting responses of all XMLHTTPRequests.

(function(open) {
  XMLHttpRequest.prototype.open = function(XMLHttpRequest) {
    var self = this;
    this.addEventListener("readystatechange", function() {
      if (this.responseText.length > 0 && 
          this.readyState == 4 && 
          this.responseURL.indexOf('www.google.com') >= 0) {

        Object.defineProperty(self, 'response', {
          get: function() { return bValue; },
          set: function(newValue) { bValue = newValue; },
          enumerable: true,
          configurable: true
        });
        self.response = 'updated value' // Intercepted Value 
      }
    }, false);
    open.apply(this, arguments);
  };
})(XMLHttpRequest.prototype.open);

我想为 fetch() API实现相同的功能.我该怎么办?

I want to implement the same feature for fetch() API. How can I do this?

推荐答案

要拦截获取请求和参数，我们可以采用下面提到的方法.它解决了我的问题.

For intercepting the fetch request and parameter we can go for below mentioned way. its resolved my issue.

 const constantMock = window.fetch;
 window.fetch = function() {
     // Get the parameter in arguments
     // Intercept the parameter here 
    return constantMock.apply(this, arguments)
 }

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