如何從ajax返回值

Question

如何獲得返回值true和false。

我總是不確定，閱讀一些文章后我仍然不明白。

我的參考： 如何從異步回調函數返回值？

            function validateScreenName(value){
            var screenname = document.getElementById("screenname-box").value;

            if((screenname.length < 3) || (screenname.length > 20)){
                value(false); // if I change to return false still can't get the value. Always undefined.
            }else{
                if(screenname != "something"){
                    var http = new XMLHttpRequest();
                    var param = "screen_name="+screenname;

                    var url = "screen-name-validation.php";
                    http.open("POST",url,true);
                    http.setRequestHeader("Content-type", "application/x-www-form-urlencoded");

                    http.onreadystatechange = function(){
                    //The response from server is either 1 or 0
                        if (http.readyState==4 && http.status==200){
                            if(http.responseText == 0){
                                value(true); // I can't get this value
                            }else{
                                value(false);
                            }
                        }
                    }
                    http.send(param);
                }else{
                    value(false);
                }
            }
        }

我需要此腳本的值

            function disableSubmit(){

            validateScreenName(function(val2){
               var val1 = validateFullName();
               var val3 = validateTargetName();
               //I need val2 from validateScreenName
               if(val1 && val2 && val3){
                   //if all true do something
               }else{
                   //if one of the value false do somthing
               }
            });         
        }

有人可以解釋如何僅使用JavaScript而沒有jquery來獲取值嗎？ 謝謝。

Answer 1

代替返回typeof bool（false，true），請使用返回字符串。例如，“ true”或“ false”