<script>
    var script = document.createElement('script');
    script.type = 'text/javascript';

    // 傳參一個(gè)回調(diào)函數(shù)名給后端，方便后端返回時(shí)執(zhí)行這個(gè)在前端定義的回調(diào)函數(shù)
    script.src = 'http://www.domain2.com:8080/login?user=admin&callback=handleCallback';
    document.head.appendChild(script);

    // 回調(diào)執(zhí)行函數(shù)
    function handleCallback(res) {
        alert(JSON.stringify(res));
    }
 </script>

handleCallback({"success": true, "user": "admin"})

this.$http = axios;
this.$http.jsonp('http://www.domain2.com:8080/login', {
    params: {},
    jsonp: 'handleCallback'
}).then((res) => {
    console.log(res); 
})

var querystring = require('querystring');
var http = require('http');
var server = http.createServer();

server.on('request', function(req, res) {
    var params = querystring.parse(req.url.split('?')[1]);
    var fn = params.callback;

    // jsonp返回設(shè)置
    res.writeHead(200, { 'Content-Type': 'text/javascript' });
    res.write(fn + '(' + JSON.stringify(params) + ')');

    res.end();
});

server.listen('8080');
console.log('Server is running at port 8080...');

GET /cors HTTP/1.1
Origin: http://api.bob.com
Host: api.alice.com
Accept-Language: en-US
Connection: keep-alive
User-Agent: Mozilla/5.0...

OPTIONS /cors HTTP/1.1
Origin: http://api.bob.com
Access-Control-Request-Method: PUT
Access-Control-Request-Headers: X-Custom-Header
Host: api.alice.com
Accept-Language: en-US
Connection: keep-alive
User-Agent: Mozilla/5.0..

var xhr = new XMLHttpRequest(); // IE8/9需用window.XDomainRequest兼容

// 前端設(shè)置是否帶cookie
xhr.withCredentials = true;

xhr.open('post', 'http://www.domain2.com:8080/login', true);
xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
xhr.send('user=admin');

xhr.onreadystatechange = function() {
    if (xhr.readyState == 4 && xhr.status == 200) {
        alert(xhr.responseText);
    }
};

var http = require('http');
var server = http.createServer();
var qs = require('querystring');

server.on('request', function(req, res) {
    var postData = '';

    // 數(shù)據(jù)塊接收中
    req.addListener('data', function(chunk) {
        postData += chunk;
    });

    // 數(shù)據(jù)接收完畢
    req.addListener('end', function() {
        postData = qs.parse(postData);

        // 跨域后臺(tái)設(shè)置
        res.writeHead(200, {
            'Access-Control-Allow-Credentials': 'true',     // 后端允許發(fā)送Cookie
            'Access-Control-Allow-Origin': 'http://www.domain1.com',    // 允許訪問的域（協(xié)議+域名+端口）
            /* 
             * 此處設(shè)置的cookie還是domain2的而非domain1，因?yàn)楹蠖艘膊荒芸缬驅(qū)慶ookie(nginx反向代理可以實(shí)現(xiàn))，
             * 但只要domain2中寫入一次cookie認(rèn)證，后面的跨域接口都能從domain2中獲取cookie，從而實(shí)現(xiàn)所有的接口都能跨域訪問
             */
            'Set-Cookie': 'l=a123456;Path=/;Domain=www.domain2.com;HttpOnly'  // HttpOnly的作用是讓js無法讀取cookie
        });

        res.write(JSON.stringify(postData));
        res.end();
    });
});

server.listen('8080');
console.log('Server is running at port 8080...');

location / {
  add_header Access-Control-Allow-Origin *;
}

#proxy服務(wù)器
server {
    listen       81;
    server_name  www.domain1.com;

    location / {
        proxy_pass   http://www.domain2.com:8080;  #反向代理
        proxy_cookie_domain www.domain2.com www.domain1.com; #修改cookie里域名
        index  index.html index.htm;

        # 當(dāng)用webpack-dev-server等中間件代理接口訪問nignx時(shí)，此時(shí)無瀏覽器參與，故沒有同源限制，下面的跨域配置可不啟用
        add_header Access-Control-Allow-Origin http://www.domain1.com;  #當(dāng)前端只跨域不帶cookie時(shí)，可為*
        add_header Access-Control-Allow-Credentials true;
    }
}

var xhr = new XMLHttpRequest();

// 前端開關(guān)：瀏覽器是否讀寫cookie
xhr.withCredentials = true;

// 訪問http-proxy-middleware代理服務(wù)器
xhr.open('get', 'http://www.domain1.com:3000/login?user=admin', true);
xhr.send();

var express = require('express');
var proxy = require('http-proxy-middleware');
var app = express();

app.use('/', proxy({
    // 代理跨域目標(biāo)接口
    target: 'http://www.domain2.com:8080',
    changeOrigin: true,

    // 修改響應(yīng)頭信息，實(shí)現(xiàn)跨域并允許帶cookie
    onProxyRes: function(proxyRes, req, res) {
        res.header('Access-Control-Allow-Origin', 'http://www.domain1.com');
        res.header('Access-Control-Allow-Credentials', 'true');
    },

    // 修改響應(yīng)信息中的cookie域名
    cookieDomainRewrite: 'www.domain1.com'  // 可以為false，表示不修改
}));

app.listen(3000);
console.log('Proxy server is listen at port 3000...');

module.exports = {
    entry: {},
    module: {},
    ...
    devServer: {
        historyApiFallback: true,
        proxy: [{
            context: '/login',
            target: 'http://www.domain2.com:8080',  // 代理跨域目標(biāo)接口
            changeOrigin: true,
            secure: false,  // 當(dāng)代理某些https服務(wù)報(bào)錯(cuò)時(shí)用
            cookieDomainRewrite: 'www.domain1.com'  // 可以為false，表示不修改
        }],
        noInfo: true
    }
}

<iframe id="iframe" src="http://child.domain.com/b.html"></iframe>
<script>
    document.domain = 'domain.com';
    var user = 'admin';
</script>

<script>
    document.domain = 'domain.com';
    // 獲取父窗口中變量
    console.log('get js data from parent ---> ' + window.parent.user);
</script>

<iframe id="iframe" src="http://www.domain2.com/b.html" style="display:none;"></iframe>
<script>
    var iframe = document.getElementById('iframe');

    // 向b.html傳hash值
    setTimeout(function() {
        iframe.src = iframe.src + '#user=admin';
    }, 1000);
    
    // 開放給同域c.html的回調(diào)方法
    function onCallback(res) {
        alert('data from c.html ---> ' + res);
    }
</script>

<iframe id="iframe" src="http://www.domain1.com/c.html" style="display:none;"></iframe>
<script>
    var iframe = document.getElementById('iframe');

    // 監(jiān)聽a.html傳來的hash值，再傳給c.html
    window.onhashchange = function () {
        iframe.src = iframe.src + location.hash;
    };
</script>

<script>
    // 監(jiān)聽b.html傳來的hash值
    window.onhashchange = function () {
        // 再通過操作同域a.html的js回調(diào)，將結(jié)果傳回
        window.parent.parent.onCallback('hello: ' + location.hash.replace('#user=', ''));
    };
</script>

var proxy = function(url, callback) {
    var state = 0;
    var iframe = document.createElement('iframe');

    // 加載跨域頁面
    iframe.src = url;

    // onload事件會(huì)觸發(fā)2次，第1次加載跨域頁，并留存數(shù)據(jù)于window.name
    iframe.onload = function() {
        if (state === 1) {
            // 第2次onload(同域proxy頁)成功后，讀取同域window.name中數(shù)據(jù)
            callback(iframe.contentWindow.name);
            destoryFrame();

        } else if (state === 0) {
            // 第1次onload(跨域頁)成功后，切換到同域代理頁面
            iframe.contentWindow.location = 'http://www.domain1.com/proxy.html';
            state = 1;
        }
    };

    document.body.appendChild(iframe);

    // 獲取數(shù)據(jù)以后銷毀這個(gè)iframe，釋放內(nèi)存；這也保證了安全（不被其他域frame js訪問）
    function destoryFrame() {
        iframe.contentWindow.document.write('');
        iframe.contentWindow.close();
        document.body.removeChild(iframe);
    }
};

// 請(qǐng)求跨域b頁面數(shù)據(jù)
proxy('http://www.domain2.com/b.html', function(data){
    alert(data);
});

<script>
    window.name = 'This is domain2 data!';
</script>

<iframe id="iframe" src="http://www.domain2.com/b.html" style="display:none;"></iframe>
<script>       
    var iframe = document.getElementById('iframe');
    iframe.onload = function() {
        var data = {
            name: 'aym'
        };
        // 向domain2傳送跨域數(shù)據(jù)
        iframe.contentWindow.postMessage(JSON.stringify(data), 'http://www.domain2.com');
    };

    // 接受domain2返回?cái)?shù)據(jù)
    window.addEventListener('message', function(e) {
        alert('data from domain2 ---> ' + e.data);
    }, false);
</script>

<script>
    // 接收domain1的數(shù)據(jù)
    window.addEventListener('message', function(e) {

        var data = JSON.parse(e.data);
        if (data) {
            data.number = 16;

            // 處理后再發(fā)回domain1
            window.parent.postMessage(JSON.stringify(data), 'http://www.domain1.com');
        }
    }, false);
</script>

<div>user input：<input type="text"></div>
<script src="https://cdn.bootcss.com/socket.io/2.2.0/socket.io.js"></script>
<script>
var socket = io('http://www.domain2.com:8080');

// 連接成功處理
socket.on('connect', function() {
    // 監(jiān)聽服務(wù)端消息
    socket.on('message', function(msg) {
        console.log('data from server: ---> ' + msg); 
    });

    // 監(jiān)聽服務(wù)端關(guān)閉
    socket.on('disconnect', function() { 
        console.log('Server socket has closed.'); 
    });
});

document.getElementsByTagName('input')[0].onblur = function() {
    socket.send(this.value);
};
</script>

var http = require('http');
var socket = require('socket.io');

// 啟http服務(wù)
var server = http.createServer(function(req, res) {
    res.writeHead(200, {
        'Content-type': 'text/html'
    });
    res.end();
});

server.listen('8080');
console.log('Server is running at port 8080...');

// 監(jiān)聽socket連接
socket.listen(server).on('connection', function(client) {
    // 接收信息
    client.on('message', function(msg) {
        client.send('hello：' + msg);
        console.log('data from client: ---> ' + msg);
    });

    // 斷開處理
    client.on('disconnect', function() {
        console.log('Client socket has closed.'); 
    });
});