axios源码分析.md

axios

lib/axios.js

// 创建axios实例
function createInstance(defaultConfig) {
  // 1. 创建实例
  var context = new Axios(defaultConfig);
  // 2. 绑定Axios构造函数原型上的request方法到创建的实例上
  var instance = bind(Axios.prototype.request, context);

  // 3. 将Axios原型扩展到实例上
  utils.extend(instance, Axios.prototype, context);

  // Copy context to instance
  utils.extend(instance, context);

  return instance;
}

// 创建一个默认
var axios = createInstance(defaults);

// 将Axios类暴露在axios实例上
axios.Axios = Axios;

// 创建一个实例的方法
axios.create = function create(instanceConfig) {
  return createInstance(mergeConfig(axios.defaults, instanceConfig));
};

// Expose Cancel & CancelToken
axios.Cancel = require('./cancel/Cancel');
axios.CancelToken = require('./cancel/CancelToken');
axios.isCancel = require('./cancel/isCancel');

// Expose all/spread
axios.all = function all(promises) {
  return Promise.all(promises);
};
axios.spread = require('./helpers/spread');

// Expose isAxiosError
axios.isAxiosError = require('./helpers/isAxiosError');

module.exports = axios;

// Allow use of default import syntax in TypeScript
module.exports.default = axios;

lib/core/Axios.js

// 构造函数
function Axios(instanceConfig) {
  this.defaults = instanceConfig;
  this.interceptors = {
    request: new InterceptorManager(),
    response: new InterceptorManager()
  };
}

/**
 * Dispatch a request
 *
 * @param {Object} config The config specific for this request (merged with this.defaults)
 */
Axios.prototype.request = function request(config) {
  /*eslint no-param-reassign:0*/
  // Allow for axios('example/url'[, config]) a la fetch API
  if (typeof config === 'string') {
    config = arguments[1] || {};
    config.url = arguments[0];
  } else {
    config = config || {};
  }

  config = mergeConfig(this.defaults, config);

  // Set config.method
  if (config.method) {
    config.method = config.method.toLowerCase();
  } else if (this.defaults.method) {
    config.method = this.defaults.method.toLowerCase();
  } else {
    config.method = 'get';
  }

  // filter out skipped interceptors
  var requestInterceptorChain = [];
  var synchronousRequestInterceptors = true;
  this.interceptors.request.forEach(function unshiftRequestInterceptors(interceptor) {
    if (typeof interceptor.runWhen === 'function' && interceptor.runWhen(config) === false) {
      return;
    }

    synchronousRequestInterceptors = synchronousRequestInterceptors && interceptor.synchronous;

    requestInterceptorChain.unshift(interceptor.fulfilled, interceptor.rejected);
  });

  var responseInterceptorChain = [];
  this.interceptors.response.forEach(function pushResponseInterceptors(interceptor) {
    responseInterceptorChain.push(interceptor.fulfilled, interceptor.rejected);
  });

  var promise;

  if (!synchronousRequestInterceptors) {
    var chain = [dispatchRequest, undefined];

    Array.prototype.unshift.apply(chain, requestInterceptorChain);
    chain.concat(responseInterceptorChain);

    promise = Promise.resolve(config);
    while (chain.length) {
      promise = promise.then(chain.shift(), chain.shift());
    }

    return promise;
  }


  var newConfig = config;
  while (requestInterceptorChain.length) {
    var onFulfilled = requestInterceptorChain.shift();
    var onRejected = requestInterceptorChain.shift();
    try {
      newConfig = onFulfilled(newConfig);
    } catch (error) {
      onRejected(error);
      break;
    }
  }

  try {
    promise = dispatchRequest(newConfig);
  } catch (error) {
    return Promise.reject(error);
  }

  while (responseInterceptorChain.length) {
    promise = promise.then(responseInterceptorChain.shift(), responseInterceptorChain.shift());
  }

  return promise;
};

Axios.prototype.getUri = function getUri(config) {
  config = mergeConfig(this.defaults, config);
  return buildURL(config.url, config.params, config.paramsSerializer).replace(/^\?/, '');
};

// Provide aliases for supported request methods
utils.forEach(['delete', 'get', 'head', 'options'], function forEachMethodNoData(method) {
  /*eslint func-names:0*/
  Axios.prototype[method] = function(url, config) {
    return this.request(mergeConfig(config || {}, {
      method: method,
      url: url,
      data: (config || {}).data
    }));
  };
});

utils.forEach(['post', 'put', 'patch'], function forEachMethodWithData(method) {
  /*eslint func-names:0*/
  Axios.prototype[method] = function(url, data, config) {
    return this.request(mergeConfig(config || {}, {
      method: method,
      url: url,
      data: data
    }));
  };
});

module.exports = Axios;