原生Ajax + Promise

有原生写的ajax + promise嫁接下

;(function(root){
    var LD = function(obj){
        if( obj instanceof LD ) return obj;
        if( !(this instanceof LD )) return new LD(obj);
    };

    root.LD = LD;

    console.log(window.LD);

    function __encodeParameter( data ){
        let tmp = "";
        if(typeof data === 'string')
            tmp = data;
        else{
            var e = encodeURIComponent;
            var params = [];
            for( let k in data ){
                if(data.hasOwnProperty( k )){
                    params.push( e(k)) +'=' + e(data[k]);
                }
            }

            tmp = params.join('&') ; //
        }

        return tmp;
    }

    function __initialize_xhr(){
        let xhr ;
        if(window.XMLHttpRequest){
            xhr = new XMLHttpRequest();
        }else if(window.ActiveXObject){
            try{
                xhr = new ActiveXObject("Msxml2.XMLHTTP");
            }catch(ex){
                console.log(ex);
                xhr = new ActiveXObject("Microsoft.XMLHTTP");
            }
        }

        return xhr;
    }

    var ajax = LD.Ajax = function( method , url , data , headers ,cb){
        let promise = new Promise(function(resolve , reject ){
             let xhr , params;
             data = data || {};
             headers = headers || {};

             try{
                 xhr  =  __initialize_xhr();
             }catch(ex){
                 console.log(ex);
             }

             params = __encodeParameter( data );
             console.log("-------"+   params);

             if(method == 'GET' && params ){
                     url += '?' + params;
                     params = null;
             }

             xhr.open( method , url );
             var content_type = 'application/x-www-form-urlencoded';
             for(var h in headers ){
                 if(headers.hasOwnProperty(h)){
                     if(h.toLowerCase() === "content-type"){
                         content_type = headers[h];
                     }else{
                         xhr.setRequestHeader(h , headers[h]);
                     }
                 }
             }

             xhr.setRequestHeader('Content-type', content_type );
             xhr.onreadystatechange  = function(){
                 if(xhr.readyState === 4 ){
                     var err = (!xhr.status || (xhr.status < 200 || xhr.status >= 300) &&
                                xhr.status !== 304 );
                     if( err === false ){
                         resolve( xhr.responseText , xhr );
                     }else{
                         reject( err , xhr );
                     }
                     //cb(err, xhr.responseText,xhr );
                 }
             };

             xhr.send(params);
        });

        return promise;
    };
})(window);

使用

LD.Ajax("GET","/refresh",null,null).then(function(data){
     console.log(data);
   },function( dt) {
    console.log("err:" + dt );
   }).catch(function(){
    console.log('catch error');
  });

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