问等效化

EN

fetch('/main/newuser',{
            method:'post',
            headers: {
                'Accept': 'application/json',
                'Content-Type': 'application/json',
            },
            body:JSON.stringify({username:'test',password:'test'})
        }).then((response)=>{
            if(response.status >= 200 && response.status < 300){
                return response;
            }else{
                var error = new Error(response.statusText);
                error.response = response;
                throw error;
            }
        }).then((response)=>{
            return response.json();
        }).then((data)=>{
            /* Process data */
        }).catch((error)=>{
            /* Catch Error */
        });