js ajax promise

promise.js

function ajax(type, url){
    return new Promise(function(resolve, reject){
        var http_request = new XMLHttpRequest();
        http_request.open(type, "http://127.0.0.1:8000/"+ url);
        http_request.onload = function() {                                                                                              
            if (http_request.status === 200){
                resolve(JSON.parse(http_request.response));
            } else {
                reject(Error(http_request.statusText));
            }
        };
        http_request.onerror = function(){
            reject(Error("network error"));
        };
        http_request.send();
    });
} 

// to use
ajax("GET", "api/articles/")                                                                                                    
.then(function(articles){                                                                                                       
    this.setState({ articles });                                                                                                
}.bind(this),                                                                                                                   
function(error){                                                                                                                
    console.log("REJECT");                                                                                                      
    console.log(error);                                                                                                         
});