呼叫AJAX的兩種寫法

寫法1:

var myObj;
var xmlhttp = new XMLHttpRequest();
xmlhttp.open("get", "json_demo.txt");
xmlhttp.send();
xmlhttp.onload = function() {
    myObj = JSON.parse(this.responseText);
    document.getElementById("demo").innerHTML = myObj.name;
};


寫法2:

var myObj;
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
        myObj = JSON.parse(this.responseText);
        document.getElementById("demo").innerHTML = myObj.name;
    }
};
xmlhttp.open("GET", "json_demo.txt", true);
xmlhttp.send();