javascript - 尝试从服务器解析并转换 JSON

Question

我正在尝试接收 JSON 字符串并将其输入到 canvasJS 图表中。我很难弄清楚如何将我的字符串转换为正常工作。这是我正在尝试的方法，但不起作用:

function loadGraph(serialNum){

    $.post("../Modules/LoadGraph_Mod/load_graph_mod.php",
    {
      submit: 'loadGraph',

      serial:serialNum


    },
    function(data,status){ 

newDataPoints=data;

                });

            var chart = new CanvasJS.Chart("chartContainer",
                {
                interactivityEnabled: true,
                zoomEnabled: true,
                          panEnabled: true,
                          backgroundColor:"#000", 


                          axisX: {  lineThickness: 1,
                lineColor: "#333",
                 interval: 4

                 ,
                 intervalType: "minutes",                   
                 valueFormatString: "h:mm",
                 labelFontColor: "#777"
                           },


                          axisY: {  tickColor:"#333",
                          gridColor: "#222",
                          lineThickness: 1,
                lineColor: "#333",
                valueFormatString: ""   ,
                maximum: 100          },
                          data: [{
                              dataPoints : newDataPoints,
                  markerType: "none",
                              color: "#9c9a0c",
                               type: "area",
                              xValueType: "dateTime"

                          }]
                      });

             chart.render();

}

我尝试过测试它，但直接插入我的服务器响应:

newDataPoints='[{"x":1483648595798,"y":62},{"x":1483648598843,"y":63},{"x":1483648601969,"y":64},{"x":1483648605088,"y":65},{"x":1483648779011,"y":0},{"x":1483648847224,"y":16}]';

这给了我错误:未定义不是一个对象。我尝试运行 JSON.parse 并最终出现错误，提示无法识别的标记“<”。

当我将字符串直接粘贴到图表中时，它会起作用，如下所示:

data: [{
                          dataPoints : [{"x":1483648595798,"y":62},{"x":1483648598843,"y":63},{"x":1483648601969,"y":64},{"x":1483648605088,"y":65},{"x":1483648779011,"y":0},{"x":1483648847224,"y":16},{"x":1483648860414,"y":17},{"x":1483648862560,"y":18},{"x":1483648865650,"y":19},{"x":1483648868773,"y":20}],
              markerType: "none",
                          color: "#9c9a0c",
                           type: "area",
                          xValueType: "dateTime"

                      }]

所以我试图弄清楚如何转换从服务器返回的 JSON 字符串，使其在我的图表中正常工作。我将不胜感激任何帮助。谢谢。

Answer 1

如果您尝试从服务器发出简单的请求并返回 JSON 对象，我会执行以下操作

var http = require('http');
http.get(yourUrl, (res) => {
    const statusCode = res.statusCode;

    let error;
    if (statusCode !== 200) {
        error = new Error('Request Failed' + statusCode);
    }

    if (error) {
        console.log(error.message);
    }

    let body = '';
    res.on('data', (chunk) => {
        //individual pre-processing here
        body += chunk;
    }).on('end', () => {
        let parsedBody = JSON.parse(body);
        //Whatever you want to do with the object
    }).on('error', (err) => {
        console.log(err);
    });
});