写在开头
前置知识内容axios的使用，JavaScript
- axios中文文档
- axios官当英文文档/github
本文对应的版本为0.18.X
下载源码
框架结构
工具函数(helper/*.js)
1.实现bind函数
框架中模拟实现了JavaScript原生的bind函数，作用相同。bind函数位于lib/helpers/bind.js,通过node模块会引入到util.js
function bind (fn,thisArg){
return function wrap(){
var args=new Array(argumnets.length);
for (var i=0;i在实现中通过遍历将函数的类数组对象arguments转为了数组。
2. 构建url的buildURL函数
函数主要用于将查询参数拼接到url地址后面，函数接受三个参数url，参数params，用于序列化params的函数paramsSerializer
function encode(val) {
return encodeURIComponent(val).
replace(/%40/gi, '@').
replace(/%3A/gi, ':').
replace(/%24/g, '$').
replace(/%2C/gi, ',').
replace(/%20/g, '+').
replace(/%5B/gi, '[').
replace(/%5D/gi, ']');
}
function buildURL(url, params, paramsSerializer) {
if (!params) {
return url;
}
var serializedParams;
if (paramsSerializer) {
serializedParams = paramsSerializer(params);
} else if (utils.isURLSearchParams(params)) {
serializedParams = params.toString();
} else {
var parts = [];
utils.forEach(params, function serialize(val, key) {
if (val === null || typeof val === 'undefined') {
return;
}
if (utils.isArray(val)) {
key = key + '[]';
} else {
val = [val];
}
utils.forEach(val, function parseValue(v) {
if (utils.isDate(v)) {
v = v.toISOString();
} else if (utils.isObject(v)) {
v = JSON.stringify(v);
}
parts.push(encode(key) + '=' + encode(v));
});
});
serializedParams = parts.join('&');
}
if (serializedParams) {
var hashmarkIndex = url.indexOf('#');
if (hashmarkIndex !== -1) {
url = url.slice(0, hashmarkIndex);
}
url += (url.indexOf('?') === -1 ? '?' : '&') + serializedParams;
}
return url;
}
函数首先会使用序列化函数对params进行序列化，如果没有传递参数。那么会检查params参数的类型是否是URLSearchParams,如果是则调用其toString方法获得参数。如果都不满足，那么会遍历params对象并将key，value进行encode，转为数组，然后将数组转为字符串。然后对serializedParams进行判断，去掉哈希，最后在和url拼接为地址，将地址返回。
3.combineURLs.js
function combineURLs(baseURL, relativeURL) {
return relativeURL
? baseURL.replace(/\/+$/, '') + '/' + relativeURL.replace(/^\/+/, '')
: baseURL;
};
函数接受两个参数，baseUrl和relativeURL，返回值为去掉baseURL的最后一个'/'和releativeURL最前面的'/'的拼接。
4.用于操作cookie的cookies.js
module.exports = (
utils.isStandardBrowserEnv() ?
// Standard browser envs support document.cookie
(function standardBrowserEnv() {
return {
write: function write(name, value, expires, path, domain, secure) {
var cookie = [];
cookie.push(name + '=' + encodeURIComponent(value));
if (utils.isNumber(expires)) {
cookie.push('expires=' + new Date(expires).toGMTString());
}
if (utils.isString(path)) {
cookie.push('path=' + path);
}
if (utils.isString(domain)) {
cookie.push('domain=' + domain);
}
if (secure === true) {
cookie.push('secure');
}
document.cookie = cookie.join('; ');
},
read: function read(name) {
var match = document.cookie.match(new RegExp('(^|;\\s*)(' + name + ')=([^;]*)'));
return (match ? decodeURIComponent(match[3]) : null);
},
remove: function remove(name) {
this.write(name, '', Date.now() - 86400000);
}
};
})() :
// Non standard browser env (web workers, react-native) lack needed support.
(function nonStandardBrowserEnv() {
return {
write: function write() {},
read: function read() { return null; },
remove: function remove() {}
};
})()
);
函数封装了对于cookie的三个操作，write，read，remove。具体实现上首先判断了环境，如果不是浏览器环境，直接返回空的函数。是浏览器环境的话，借助于数组实现了write函数，借助于正则实现了read，通过将cookie的有效期设置为前一天来清除cookie。
5.deprecatedMethod.js
module.exports = function deprecatedMethod(method, instead, docs) {
try {
console.warn(
'DEPRECATED method `' + method + '`.' +
(instead ? ' Use `' + instead + '` instead.' : '') +
' This method will be removed in a future release.');
if (docs) {
console.warn('For more information about usage see ' + docs);
}
} catch (e) { /* Ignore */ }
};
当方法被弃用时，打印警告信息
6.isAbsoluteURL
module.exports = function isAbsoluteURL(url) {
// A URL is considered absolute if it begins with "://" or "//" (protocol-relative URL).
// RFC 3986 defines scheme name as a sequence of characters beginning with a letter and followed
// by any combination of letters, digits, plus, period, or hyphen.
return /^([a-z][a-z\d\+\-\.]*:)?\/\//i.test(url);
};
7.isURLSameOrigin
module.exports = (
utils.isStandardBrowserEnv() ?
// Standard browser envs have full support of the APIs needed to test
// whether the request URL is of the same origin as current location.
(function standardBrowserEnv() {
// 判断是不是IE
var msie = /(msie|trident)/i.test(navigator.userAgent);
var urlParsingNode = document.createElement('a');
var originURL;
/**
* Parse a URL to discover it's components
*
* @param {String} url The URL to be parsed
* @returns {Object}
*/
function resolveURL(url) {
var href = url;
if (msie) {
// IE needs attribute set twice to normalize properties
urlParsingNode.setAttribute('href', href);
href = urlParsingNode.href;
}
urlParsingNode.setAttribute('href', href);
// urlParsingNode provides the UrlUtils interface - http://url.spec.whatwg.org/#urlutils
return {
href: urlParsingNode.href,
protocol: urlParsingNode.protocol ? urlParsingNode.protocol.replace(/:$/, '') : '',
host: urlParsingNode.host,
search: urlParsingNode.search ? urlParsingNode.search.replace(/^\?/, '') : '',
hash: urlParsingNode.hash ? urlParsingNode.hash.replace(/^#/, '') : '',
hostname: urlParsingNode.hostname,
port: urlParsingNode.port,
pathname: (urlParsingNode.pathname.charAt(0) === '/') ?
urlParsingNode.pathname :
'/' + urlParsingNode.pathname
};
}
originURL = resolveURL(window.location.href);
/**
* Determine if a URL shares the same origin as the current location
*
* @param {String} requestURL The URL to test
* @returns {boolean} True if URL shares the same origin, otherwise false
*/
return function isURLSameOrigin(requestURL) {
var parsed = (utils.isString(requestURL)) ? resolveURL(requestURL) : requestURL;
return (parsed.protocol === originURL.protocol &&
parsed.host === originURL.host);
};
})() :
// Non standard browser envs (web workers, react-native) lack needed support.
(function nonStandardBrowserEnv() {
return function isURLSameOrigin() {
return true;
};
})()
);
判断是否同源
前提：需要了解浏览器的navigator基本属性。
函数首先判断了当前的运行环境，非浏览器环境不存在跨域问题，直接返回false。
浏览器环境首先创建了一个函数用于解析绝对的url地址resolveURl。然后分别解析window.location.href和传入的参数，比较协议和域名是否相同。
resolveURL中借助于a标签对url进行解析，解析过程中处理了IE浏览器需要设置两次href的问题。
引申思考怎么对url进行解析，方式有哪些。
8.normalizeHeaderName.js
function normalizeHeaderName(headers, normalizedName) {
utils.forEach(headers, function processHeader(value, name) {
if (name !== normalizedName && name.toUpperCase() === normalizedName.toUpperCase()) {
headers[normalizedName] = value;
delete headers[name];
}
});
};
对对象属性名的进行格式化，删除，新建符合大小写规范的属性。
9.parseHeaders.js
// Headers whose duplicates are ignored by node
// c.f. https://nodejs.org/api/http.html#http_message_headers
var ignoreDuplicateOf = [
'age', 'authorization', 'content-length', 'content-type', 'etag',
'expires', 'from', 'host', 'if-modified-since', 'if-unmodified-since',
'last-modified', 'location', 'max-forwards', 'proxy-authorization',
'referer', 'retry-after', 'user-agent'
];
/**
* Parse headers into an object
*
* ```
* Date: Wed, 27 Aug 2014 08:58:49 GMT
* Content-Type: application/json
* Connection: keep-alive
* Transfer-Encoding: chunked
* ```
*
* @param {String} headers Headers needing to be parsed
* @returns {Object} Headers parsed into an object
*/
module.exports = function parseHeaders(headers) {
var parsed = {};
var key;
var val;
var i;
if (!headers) { return parsed; }
utils.forEach(headers.split('\n'), function parser(line) {
i = line.indexOf(':');
key = utils.trim(line.substr(0, i)).toLowerCase();
val = utils.trim(line.substr(i + 1));
if (key) {
if (parsed[key] && ignoreDuplicateOf.indexOf(key) >= 0) {
return;
}
if (key === 'set-cookie') {
parsed[key] = (parsed[key] ? parsed[key] : []).concat([val]);
} else {
parsed[key] = parsed[key] ? parsed[key] + ', ' + val : val;
}
}
});
return parsed;
};
将响应的head转为字符串
10.spread.js
函数的作用是将参数展开。因为axios.all().then(callback)中callback函数接受的是一个数组，为了方便使用，将其转化为了一各个的参数。
function spread(callback) {
return function wrap(arr) {
return callback.apply(null, arr);
};
};
工具函数(util.js)
util主要有四个主要的函数实现了forEach，merge，deepmerge，exten
基本类型判断
var toString = Object.prototype.toString;
function isArray(val) {
return toString.call(val) === '[object Array]';
}
function isArrayBuffer(val) {
return toString.call(val) === '[object ArrayBuffer]';
}
function isFormData(val) {
return (typeof FormData !== 'undefined') && (val instanceof FormData);
}
function isArrayBufferView(val) {
var result;
if ((typeof ArrayBuffer !== 'undefined') && (ArrayBuffer.isView)) {
result = ArrayBuffer.isView(val);
} else {
result = (val) && (val.buffer) && (val.buffer instanceof ArrayBuffer);
}
return result;
}
function isString(val) {
return typeof val === 'string';
}
function isNumber(val) {
return typeof val === 'number';
}
function isUndefined(val) {
return typeof val === 'undefined';
}
function isObject(val) {
return val !== null && typeof val === 'object';
}
function isDate(val) {
return toString.call(val) === '[object Date]';
}
function isFile(val) {
return toString.call(val) === '[object File]';
}
function isBlob(val) {
return toString.call(val) === '[object Blob]';
}
function isFunction(val) {
return toString.call(val) === '[object Function]';
}
function isStream(val) {
return isObject(val) && isFunction(val.pipe);
}
function isURLSearchParams(val) {
return typeof URLSearchParams !== 'undefined' && val instanceof URLSearchParams;
}
实现了一下trime方法
function trim(str) {
return str.replace(/^\s*/, '').replace(/\s*$/, '');
}
/**
* Determine if we're running in a standard browser environment
*
* This allows axios to run in a web worker, and react-native.
* Both environments support XMLHttpRequest, but not fully standard globals.
*
* web workers:
* typeof window -> undefined
* typeof document -> undefined
*
* react-native:
* navigator.product -> 'ReactNative'
* nativescript
* navigator.product -> 'NativeScript' or 'NS'
*/
function isStandardBrowserEnv() {
if (typeof navigator !== 'undefined' &&
(navigator.product === 'ReactNative' ||
navigator.product === 'NativeScript' ||
navigator.product === 'NS')) {
return false;
}
return (
typeof window !== 'undefined' &&
typeof document !== 'undefined'
);
}
/**
* Iterate over an Array or an Object invoking a function for each item.
*
* If `obj` is an Array callback will be called passing
* the value, index, and complete array for each item.
*
* If 'obj' is an Object callback will be called passing
* the value, key, and complete object for each property.
*
* @param {Object|Array} obj The object to iterate
* @param {Function} fn The callback to invoke for each item
*/
function forEach(obj, fn) {
// Don't bother if no value provided
if (obj === null || typeof obj === 'undefined') {
return;
}
// Force an array if not already something iterable
if (typeof obj !== 'object') {
/*eslint no-param-reassign:0*/
obj = [obj];
}
if (isArray(obj)) {
// Iterate over array values
for (var i = 0, l = obj.length; i < l; i++) {
fn.call(null, obj[i], i, obj);
}
} else {
// Iterate over object keys
for (var key in obj) {
if (Object.prototype.hasOwnProperty.call(obj, key)) {
fn.call(null, obj[key], key, obj);
}
}
}
}
/**
* Accepts varargs expecting each argument to be an object, then
* immutably merges the properties of each object and returns result.
*
* When multiple objects contain the same key the later object in
* the arguments list will take precedence.
*
* Example:
*
* ```js
* var result = merge({foo: 123}, {foo: 456});
* console.log(result.foo); // outputs 456
* ```
*
* @param {Object} obj1 Object to merge
* @returns {Object} Result of all merge properties
*/
function merge(/* obj1, obj2, obj3, ... */) {
var result = {};
function assignValue(val, key) {
if (typeof result[key] === 'object' && typeof val === 'object') {
result[key] = merge(result[key], val);
} else {
result[key] = val;
}
}
for (var i = 0, l = arguments.length; i < l; i++) {
forEach(arguments[i], assignValue);
}
return result;
}
/**
* Function equal to merge with the difference being that no reference
* to original objects is kept.
*
* @see merge
* @param {Object} obj1 Object to merge
* @returns {Object} Result of all merge properties
*/
function deepMerge(/* obj1, obj2, obj3, ... */) {
var result = {};
function assignValue(val, key) {
if (typeof result[key] === 'object' && typeof val === 'object') {
result[key] = deepMerge(result[key], val);
} else if (typeof val === 'object') {
result[key] = deepMerge({}, val);
} else {
result[key] = val;
}
}
for (var i = 0, l = arguments.length; i < l; i++) {
forEach(arguments[i], assignValue);
}
return result;
}
/**
* Extends object a by mutably adding to it the properties of object b.
*
* @param {Object} a The object to be extended
* @param {Object} b The object to copy properties from
* @param {Object} thisArg The object to bind function to
* @return {Object} The resulting value of object a
*/
function extend(a, b, thisArg) {
forEach(b, function assignValue(val, key) {
if (thisArg && typeof val === 'function') {
a[key] = bind(val, thisArg);
} else {
a[key] = val;
}
});
return a;
}
扩展阅读：
https://www.jianshu.com/p/22b49e6ad819 封装不会获取重复的数据。