ajax.js

(function (root) {
    var Ajax = function () {
        this.setajax = {};
        this.xmlhttp = {};
    };
    Ajax.prototype.open = function (s) {
        var async, method, url, self = this;
        this.setajax = s;
        try {
            if (!this.setajax.url) {
                throw 'Você deve informar a url.';
            }
            if (typeof this.setajax === 'object') {
                if (root.XMLHttpRequest) {
                    // IE7+, Firefox, Chrome, Opera, Safari
                    this.xmlhttp = new XMLHttpRequest();
                } else {
                    // IE6, IE5
                    this.xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
                }
                this.xmlhttp.onreadystatechange = function () {
                    if (self.xmlhttp.readyState === 4 && self.xmlhttp.status === 200) {
                        if (self.setajax.dataType === 'json') {
                            try{
                                self.setajax.responseText = JSON.parse(self.xmlhttp.responseText);
                            } catch (err){
                                self.setajax.responseText = eval('(' + self.xmlhttp.responseText + ')');
                            }
                        } else {
                            self.setajax.responseText = self.xmlhttp.responseText;
                        }
                    }
                };
                method = this.setajax.method || 'GET';
                url = this.setajax.url || root.location.href;
                async = this.setajax.async || false;
                this.xmlhttp.open(method, url, async);
                this.xmlhttp.setRequestHeader("X-Requested-With", "XMLHttpRequest");
                if (this.setajax.data) {
                    this.xmlhttp.setRequestHeader("Content-Type", "application/json;charset=UTF-8");
                    this.xmlhttp.send(JSON.stringify(this.setajax.data));
                } else {
                    this.xmlhttp.send();
                }
                if (this.setajax.success && typeof this.setajax.success === 'function') {
                    this.setajax.success(this.setajax.responseText);
                }
            } else {
                throw 'Você deve passar um objeto.';
            }
        } catch (e) {
            if (this.setajax.error && typeof this.setajax.error === 'function') {
                this.setajax.error(e);
            }
        }

        return this.xmlhttp;
    };
    root['Ajax'] = new Ajax();
}(this));