原生JS写的ajax函数

参照JQuery中的ajax功能，用原生JS写了一个ajax，功能相对JQuery要少很多，不过基本功能都有，包括JSONP。

调用的方式分为两种：

1. ajax(url, {});

2. ajax({});

调用的方法参照JQuery的ajax，只是 不需要写$.ajax ，只需要写 ajax 就可以了。

代码如下：

!function () {
    var jsonp_idx = 1;

    var ajax = function (url, options) {
        if (typeof url === "object") {
            options = url;
            url = undefined;
        }
        var o = {
            async: options.async === false ? false : true,
            url: url || options.url || '',
            data: options.data || null,
            type: (options.type || 'POST').toUpperCase(),
            dataType: (options.dataType || 'JSON').toUpperCase(), //text,json,jsonp,html,xml
            contentType: options.contentType || "application/x-www-form-urlencoded; charset=utf-8",
            jsonp: options.jsonp || "callback",
            jsonpCallback: options.jsonpCallback || '',
            callback: options.callback || options.success || null,
            error: options.error || null,
            timeout: options.timeout || 4000,
            result: ''
        };

        if (o.dataType === 'JSONP' && o.jsonp !== false) {
            return ajaxJSONP(o.url, o.jsonp, o.jsonpCallback, o.callback) || false;
        }

        if (o.async === true && typeof o.callback !== 'function') {
            return false;
        }

        if (o.dataType === 'HTML' || checkStaticFile(o.url)) {
            //由于大多数WEB服务器不允许静态文件响应POST请求（会返回 405 Method Not Allowed），所以改为GET请求
            o.type = 'GET';
            o.url += (/\?/.test(o.url) ? "&" : "?") + new Date().getTime();
        }

        var xhr = new XmlHttpRequest();

        if (o.async === true) {
            xhr.timeout = o.timeout;
        }

        xhr.open(o.type, o.url, o.async);

        xhr.onreadystatechange = function () {
            if (4 === xhr.readyState) {
                o.result = xhr.responseText;
                if (200 === xhr.status) {
                    switch (o.dataType) {
                        case 'JSON':
                            o.result = parseJSON(o.result);
                            break;
                        case 'XML':
                            o.result = parseXML(xhr.responseXML);
                            break;
                    }
                    if (typeof o.callback === 'function') {
                        o.callback(o.result, xhr.statusText, xhr);

                        if (o.dataType === 'HTML') {
                            //执行HTML文件中的JS代码
                            execScript(o.result);
                        }
                    }
                } else {
                    typeof o.error === 'function' ? function () { o.error(o.result, xhr.statusText, xhr); }() : throwError(o.result);
                }
                xhr = null;
            }
        };

        if ('POST' === o.type) {
            xhr.setRequestHeader("content-type", o.contentType);
        }

        xhr.send(o.data);

        if (o.async === false) {
            return o.result;
        }
    };

    function XmlHttpRequest() {
        return function () {
            var len = arguments.length;
            for (var i = 0; i < len; i++) {
                try { return arguments[i](); } catch (e) { }
            }
        }(function () { return new XMLHttpRequest() },
		function () { return new ActiveXObject('Msxml2.XMLHTTP') },
		function () { return new ActiveXObject('Microsoft.XMLHTTP') });
    }

    function ajaxJSONP(url, jsonp, jsonpCallback, callback) {
        //if (!jsonpCallback) {
        //不管有没有指定JSONP回调函数，都自动生成回调函数，然后取出数据给ajax回调函数
        if (!jsonpCallback || true) {
            jsonpCallback = 'jsonpCallback_' + new Date().getTime() + '_' + jsonp_idx++;

            window[jsonpCallback] = function (result) {
                removeScript(jsonpCallback);
                callback(result);
            };
        }

        url += (/\?/.test(url) ? "&" : "?") + jsonp + "=" + jsonpCallback;

        return createScript(jsonpCallback, url);
    }

    function createScript(id, src) {
        var obj = document.createElement("script");
        obj.id = id;
        obj.type = "text/javascript";
        obj.src = src;
        document.getElementsByTagName("head")[0].appendChild(obj);

        return obj;
    }

    function removeScript(id) {
        var script = document.getElementById(id), head = document.getElementsByTagName("head")[0];
        if (head && script != null && script.parentNode) {
            head.removeChild(script);
        }
    }

    function checkStaticFile(url) {
        url = (url || '').split('?')[0];
        var ext = url.substr(url.lastIndexOf('.'));

        return /(html|htm|txt|json)/ig.test(ext);
    }

    function execScript(html) {
        var ms = html.match(/<script(.|\n)*?>(.|\n|\r\n)*?<\/script>/ig);
        if (ms) {
            var len = ms.length;
            for (var i = 0; i < len; i++) {
                var m = ms[i].match(/<script(.|\n)*?>((.|\n|\r\n)*)?<\/script>/im);
                if (m[2]) {
                    if (window.execScript) {
                        window.execScript(m[2]);
                    } else {
                        //window.eval(m[2]);
                        (function (data) {
                            return (new Function("return " + data))();
                        })(m[2].replace(/(^[\s]*)|([\s]*$)/g, ''));
                    }
                }
            }
        }
    }

    function throwError(err) {
        try {
            console.trace();
            console.log('data:\r\n\t', err);
        } catch (e) { }
        throw new Error(err);
    }

    function parseJSON(data) {
        if (typeof data !== "string" || !data) {
            return null;
        }
        if (typeof JSON2 === 'object') {
            return JSON2.parse(data);
        } else if (typeof JSON === 'object') {
            return JSON.parse(data);
        } else {
            return (new Function("return " + data))();
        }

        throwError("Invalid JSON: " + data);
    }

    function parseXML(data) {
        if (typeof data !== "string" || !data) {
            return null;
        }
        var xml, tmp;
        try {
            if (window.DOMParser) { // Standard
                tmp = new DOMParser();
                xml = tmp.parseFromString(data, "text/xml");
            } else { // IE
                xml = new ActiveXObject("Microsoft.XMLDOM");
                xml.async = "false";
                xml.loadXML(data);
            }
        } catch (e) {
            xml = undefined;
        }
        if (!xml || !xml.documentElement || xml.getElementsByTagName("parsererror").length) {
            throwError("Invalid XML: " + data);
        }
        return xml;
    }

    window.ajax = ajax;
}();

　　　　

压缩后的代码：

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