Question

收到响应没有任何问题，但是在接收数据响应后必须更改的属性未定义。可能他们从临时变量获取的值太快了。如何解决这个问题？顺便说一句，是否有一个选项可以避免那些临时变量并使用if语句中的对象属性？它会好得多。尝试了不同的方式，但它没有工作=（

  var tickerBittrex = function(tickerName)
    {
        this.tickerName = tickerName;
        this.requestURL = "https://bittrex.com/api/v1.1/public/getticker?market=" + tickerName;
        /* Properties */
        this.success = false;
        this.message = "";
        this.Last = 0;


        this.sendRequest = function()
        {   /* temp variables */
            var success;
            var message;
            var Last;

            var xhttp = new XMLHttpRequest();

            xhttp.onreadystatechange = function(success, message, Last)
            {
                if (this.readyState == 4 && this.status == 200)
                {
                   console.log(xhttp.responseText); // test

                   var response = JSON.parse(xhttp.responseText); // parsed response

                   console.log(response); // test

                   success = response.success;
                   message = response.message;

                   Last = response.result.Last;

                   console.log(Last); // test

                   console.log("xhttp.status: " + xhttp.status + " readyStat:" + xhttp.readyStat); // test

                }
            };
            xhttp.open("GET", this.requestURL, true);
            xhttp.send();

            this.success = success;
            this.message = message;
            this.Last = Last;
        }

    }


    var bittrexBTC = new tickerBittrex("usdt-btc");
    bittrexBTC.sendRequest();

Answer 1

这应该有效：

    var tickerBittrex = function(tickerName) {
        this.tickerName = tickerName;
        this.requestURL = "https://bittrex.com/api/v1.1/public/getticker?market=" + tickerName;
        /* Properties */
        this.success = false;
        this.message = "";
        this.Last = 0;
        var self = this;

        this.sendRequest = function() { /* temp variables */


            var xhttp = new XMLHttpRequest();

            xhttp.onreadystatechange = function(success, message, Last) {
                var success;
                var message;
                var Last;
                if (this.readyState == 4 && this.status == 200) {
                    console.log(xhttp.responseText); // test

                    var response = JSON.parse(xhttp.responseText); // parsed response

                    console.log(response); // test

                    success = response.success;
                    message = response.message;

                    Last = response.result.Last;

                    console.log(Last, success, message); // test
                    self.success = success;
                    self.message = message;
                    self.Last = Last;
                    console.log(self);
                    console.log("xhttp.status: " + xhttp.status + " readyState:" + xhttp.readyState); // test                   

                }
            };
            xhttp.open("GET", this.requestURL, true);
            xhttp.send();

        }


    }


    var bittrexBTC = new tickerBittrex("usdt-btc");
    bittrexBTC.sendRequest();

说明：

首先，将下面的代码放在onreadystatechange回调中，因为在回调执行成功的值之前，消息，Last将是未定义的。

       this.success = success;
        this.message = message;
        this.Last = Last;

第二个：将此更改为在tickerBittrex函数中定义的self，因此可以使此对象正确。

        var self = this;

所以：

       self.success = success;
        self.message = message;
        self.Last = Last;

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1 个答案: