34. 实现对 Ajax 事件请求的监听 about fe-questions HOT 1 OPEN

function ajax(options) {
    options = options || {};
    options.type = (options.type || "GET").toUpperCase();
    options.dataType = options.dataType || "json";
    var params = formatParams(options.data);

    if (window.XMLHttpRequest) {
        var xhr = new XMLHttpRequest();
    } else {
        var xhr = new ActiveXObject('Microsoft.XMLHTTP');
    }

    xhr.onreadystatechange = function() {
        if (xhr.readyState == 4) {
            if (status >= 200 && status < 300 || status == 304) {
                options.success && options.success(xhr.responseText, xhr.responseXML);
            } else {
                options.fail && options.fail(status);
            }
        }
    }

    if (options.type == "GET") {
        xhr.open("GET", options.url + "?" + params, true);
        xhr.send(null);
    } else if (options.type == "POST") {
        xhr.open("POST", options.url, true);
        xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
        xhr.send(params);
    }
}

function formatParams(data) {
    var arr = [];
    for (var name in data) {
        arr.push(encodeURIComponent(name)+"="+encodeURIComponent(data[name]));
    }
    arr.push("v="+Math.random()).replace(".","");
    return arr.join("&");
}