Ajax下

一、cors跨域请求

document.onclick = function(){
  var xhr = new XMLHttpRequest();
  xhr.open("GET", "http://localhost:8080/", true);
  xhr.send();
  xhr.onreadystatechange = function(){
    if(xhr.readyState == 4){
      if((xhr.status >= 200 && xhr.status < 300) || xhr.status == 304){
        var message = xhr.responseText;
        alert(message);
      }
    }
  }
}

var http = require("http");
var arr = ["baidu.com", "taobao.com"];
http.createServer(function(req, res){
  if(arr.indexOf(req.headers["origin"]) != -1){
    res.setHeader("Access-Control-Allow-Origin", "*");
  }
  res.write("111");
  res.end();
}).listen(8080)

二、jsonp
百度搜索的例子

var headEle = document.getElementsByTagName("head")[0];

document.onclick = function(){
  var scriptEle = document.createElement("script");
  scriptEle.src = "https://sp0.baidu.com/5a1Fazu8AA54nxGko9WTAnF6hhy/su?wd=a&cb=fnShow";
  headEle.appendChild(scriptEle);
}
function fnShow(json){
  console.log(json.s);
}

jsonp.html

var headEle = document.getElementsByTagName("head")[0];
document.onclick = function(){
  var scriptEle = document.createElement("script");
  scriptEle.src = "http://localhost:8081/sum?a=4&b=38&callback=fnSum";
  headEle.appendChild(scriptEle);
}
function fnSum(json){
  alert(json);
}

jsonp.js

var http = require("http");
var url = require("url");

http.createServer(function(req, res){
  var url_sum = url.parse(req.url, true).query;
  var url_a = url_sum["a"];
  var url_b = url_sum["b"];
  var url_cb = url_sum["callback"];

  res.write(url_cd +"(" + (url_a*1+url_b*1) + ")");
  res.end()
}).listen(8001)