摘要：總體概述主要五個對象組成請求偽造對象請求跟蹤對象請求攔截對象用作對偽造的請求做出響應(yīng)。請求攔截跟蹤對象參數(shù)解析輔助函數(shù)函數(shù)結(jié)構(gòu)很明顯，判定一個數(shù)組是否包含某一個值。主要負(fù)責(zé)值的解析。若決定調(diào)用，則遍歷結(jié)束，返回該對象。

jasmine-ajax主要五個對象組成：

請求偽造對象(FackXMLHttpRequest)：

function FakeXMLHttpRequest() {}

請求跟蹤對象(RequestTracker)：

function RequestTracker() {}

請求攔截對象(RequestStub)：用作對偽造的AJAX請求做出響應(yīng)。

function RequestStub(url, stubData, method) {}

請求攔截跟蹤對象(StubTracker):

function StubTracker() {}

參數(shù)解析(ParamParser)：

function ParamParser() {}

function arrayContains(arr, item) {
for (var i = 0; i < arr.length; i++) {
  if (arr[i] === item) {
    return true;
  }
}
return false;
}

函數(shù)結(jié)構(gòu)很明顯，判定一個數(shù)組是否包含某一個值。

function extend(destination, source, propertiesToSkip) {
    propertiesToSkip = propertiesToSkip || [];
    for (var property in source) {
      if (!arrayContains(propertiesToSkip, property)) {
        destination[property] = source[property];
      }
    }
    return destination;
  }

此函數(shù)實(shí)現(xiàn)對象擴(kuò)展，propertiesToSkip參數(shù)為source中需排除掉的鍵，余下的鍵值對覆蓋寫入destination。

  if (typeof window === "undefined" && typeof exports === "object") {
    exports.MockAjax = MockAjax;
    jasmine.Ajax = new MockAjax(exports);
  } else {
    window.MockAjax = MockAjax;
    jasmine.Ajax = new MockAjax(window);
  }

首先判定是否commonjs環(huán)境，不是則傳遞window變量。在describe內(nèi)部，即可訪問通過jasmine.Ajax使用MockAjax對象。

其實(shí)結(jié)構(gòu)非常明顯，使用jasmine.Ajax.requests即可訪問到RequestTracker對象,然后通過first, mostRecent, at, filter 等方法獲取仿造的request對象，多用于對HTTP請求對象進(jìn)行判定，如方法，路徑，數(shù)據(jù)，headers等等，需要重點(diǎn)關(guān)注。reset, track手動調(diào)用意義不大，前者用于重置變量環(huán)境，后者在生成偽造XHR時調(diào)用。

 function RequestTracker() {
    var requests = [];

    this.track = function(request) {
      requests.push(request);
    };

    this.first = function() {
      return requests[0];
    };

    this.count = function() {
      return requests.length;
    };

    this.reset = function() {
      requests = [];
    };

    this.mostRecent = function() {
      return requests[requests.length - 1];
    };

    this.at = function(index) {
      return requests[index];
    };

    this.filter = function(url_to_match) {
      if (requests.length === 0) { return []; }
      var matching_requests = [];

      for (var i = 0; i < requests.length; i++) {
        if (url_to_match instanceof RegExp &&
            url_to_match.test(requests[i].url)) {
            matching_requests.push(requests[i]);
        } else if (url_to_match instanceof Function &&
            url_to_match(requests[i])) {
            matching_requests.push(requests[i]);
        } else {
          if (requests[i].url === url_to_match) {
            matching_requests.push(requests[i]);
          }
        }
      }
      return matching_requests;
    };
  }

通過jasmine.Ajax.stubs即可訪問到StubTracker對象，主動調(diào)用意義不大。reset方法用于變量環(huán)境重置，addStub方法在生成RequestStub對象時調(diào)用。findStub在xhr.open()調(diào)用時，判定是否定義過response。

  function StubTracker() {
    var stubs = [];

    this.addStub = function(stub) {
      stubs.push(stub);
    };

    this.reset = function() {
      stubs = [];
    };

    this.findStub = function(url, data, method) {
      for (var i = stubs.length - 1; i >= 0; i--) {
        var stub = stubs[i];
        if (stub.matches(url, data, method)) {
          return stub;
        }
      }
    };
  }

請求攔截在url, stubData, method同時匹配的情況下才會啟動攔截。

 function RequestStub(url, stubData, method) {
    var normalizeQuery = function(query) {
      return query ? query.split("&").sort().join("&") : undefined;
    };

    if (url instanceof RegExp) {
      this.url = url;
      this.query = undefined;
    } else {
      var split = url.split("?");
      this.url = split[0];
      this.query = split.length > 1 ? normalizeQuery(split[1]) : undefined;
    }

    this.data = normalizeQuery(stubData);
    this.method = method;

    this.andReturn = function(options) {
      this.status = options.status || 200;

      this.contentType = options.contentType;
      this.responseText = options.responseText;
    };

    this.matches = function(fullUrl, data, method) {
      var matches = false;
      fullUrl = fullUrl.toString();
      if (this.url instanceof RegExp) {
        matches = this.url.test(fullUrl);
      } else {
        var urlSplit = fullUrl.split("?"),
            url = urlSplit[0],
            query = urlSplit[1];
        matches = this.url === url && this.query === normalizeQuery(query);
      }
      return matches && (!this.data || this.data === normalizeQuery(data)) && (!this.method || this.method === method);
    };
  }

主要負(fù)責(zé)值的解析。paramParsers參數(shù)為parser對象數(shù)組。findParser遍歷paramParsers，通過test屬性判定是否啟用對應(yīng)的parse方法處理數(shù)據(jù)。若決定調(diào)用，則遍歷結(jié)束，返回該對象。add方法一般會通過jasmine.Ajax.addCustomParamParser(parser)調(diào)用，優(yōu)先級上，后添加的>先添加的>默認(rèn)的。

  function ParamParser() {
    var defaults = [
      {
        test: function(xhr) {
          return (/^application/json/).test(xhr.contentType());
        },
        parse: function jsonParser(paramString) {
          return JSON.parse(paramString);
        }
      },
      {
        test: function(xhr) {
          return true;
        },
        parse: function naiveParser(paramString) {
          var data = {};
          var params = paramString.split("&");

          for (var i = 0; i < params.length; ++i) {
            var kv = params[i].replace(/+/g, " ").split("=");
            var key = decodeURIComponent(kv[0]);
            data[key] = data[key] || [];
            data[key].push(decodeURIComponent(kv[1]));
          }
          return data;
        }
      }
    ];
    var paramParsers = [];

    this.add = function(parser) {
      paramParsers.unshift(parser);
    };

    this.findParser = function(xhr) {
        for(var i in paramParsers) {
          var parser = paramParsers[i];
          if (parser.test(xhr)) {
            return parser;
          }
        }
    };

    this.reset = function() {
      paramParsers = [];
      for(var i in defaults) {
        paramParsers.push(defaults[i]);
      }
    };

    this.reset();
  }

代碼過長，分段說明。

FakeXMLHttpRequest
實(shí)例化后，即添加進(jìn)入requestTracker，便于后期訪問。

function FakeXMLHttpRequest() {
  requestTracker.track(this);
  this.requestHeaders = {};
  this.overriddenMimeType = null;
}

原型繼承
此處感覺比較好玩，是繼承真的XMLHttpRequest對象，只是去掉幾個特殊鍵值對，后面會進(jìn)行處理。

var iePropertiesThatCannotBeCopied = ["responseBody", "responseText", "responseXML", "status", "statusText", "responseTimeout"];
    extend(FakeXMLHttpRequest.prototype, new window.XMLHttpRequest(), iePropertiesThatCannotBeCopied);

Request偽造
熟悉原生ajax的應(yīng)該很容易看懂。重點(diǎn)在于，send方法調(diào)用時，會立即在stubs里尋找匹配當(dāng)前url,method,data的響應(yīng)攔截器，如果預(yù)定義過了，則會立刻傳遞給response函數(shù)進(jìn)行響應(yīng)，否則需要之后手動調(diào)用response函數(shù)進(jìn)行響應(yīng)。

    extend(FakeXMLHttpRequest.prototype, {

      open: function() {
        this.method = arguments[0];
        this.url = arguments[1];
        this.username = arguments[3];
        this.password = arguments[4];
        this.readyState = 1;
        this.onreadystatechange();
      },

      setRequestHeader: function(header, value) {
        if(this.requestHeaders.hasOwnProperty(header)) {
          this.requestHeaders[header] = [this.requestHeaders[header], value].join(", ");
        } else {
          this.requestHeaders[header] = value;
        }
      },

      overrideMimeType: function(mime) {
        this.overriddenMimeType = mime;
      },

      abort: function() {
        this.readyState = 0;
        this.status = 0;
        this.statusText = "abort";
        this.onreadystatechange();
      },

      readyState: 0,

      onload: function() {
      },

      onreadystatechange: function(isTimeout) {
      },

      status: null,

      send: function(data) {
        this.params = data;
        this.readyState = 2;
        this.onreadystatechange();

        var stub = stubTracker.findStub(this.url, data, this.method);
        if (stub) {
          this.response(stub);
        }
      },

      contentType: function() {
        return findHeader("content-type", this.requestHeaders);
      },

      data: function() {
        if (!this.params) {
          return {};
        }

        return paramParser.findParser(this).parse(this.params);
      },

      getResponseHeader: function(name) {
        return findHeader(name, this.responseHeaders);
      },

      getAllResponseHeaders: function() {
        var responseHeaders = [];
        for (var i in this.responseHeaders) {
          if (this.responseHeaders.hasOwnProperty(i)) {
            responseHeaders.push(i + ": " + this.responseHeaders[i]);
          }
        }
        return responseHeaders.join("
");
      },

      responseText: null,

      response: function(response) {
        if (this.readyState === 4) {
          throw new Error("FakeXMLHttpRequest already completed");
        }
        this.status = response.status;
        this.statusText = response.statusText || "";
        this.responseText = response.responseText || "";
        this.readyState = 4;
        this.responseHeaders = response.responseHeaders ||
          {"Content-Type": response.contentType || "application/json" };

        this.onload();
        this.onreadystatechange();
      },

      responseTimeout: function() {
        if (this.readyState === 4) {
          throw new Error("FakeXMLHttpRequest already completed");
        }
        this.readyState = 4;
        jasmine.clock().tick(30000);
        this.onreadystatechange("timeout");
      }
    });

    return FakeXMLHttpRequest;
  }

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