从node.js中获取Chart.js的数据

Question

我想从节点js（res.render（'report'，{result：result}）获取我渲染的数据，并用它与Chart.js制作图表。我可以渲染它们，但无法打印出来从客户端javascript。请在这个主题上为我提供帮助。感谢您的宝贵时间。

          <div class="item" style="width: 98%; height: 80%;">
          <canvas id="myChart" style="width: 50%; height: 50%;"></canvas>
          <%a=result;%>
          <script type="text/javascript">
               k();
               var ctx = document.getElementById('myChart').getContext('2d');
               var chart = new Chart(ctx, {
                   type: 'line',
                   data: {
                       labels: ['Morning', 'Afternoon', 'Night'],
                       datasets: [{
                           label: 'My First dataset',
                           backgroundColor: 'rgb(255, 99, 132)',
                           borderColor: 'rgb(255, 99, 132)',
                           data: [0, 10, 5, 2, 20, 30, 45]
                       }]
                   },

                   options: {}
                   });

             async function k()
             {
                   var a = result;
                   console.log(a[0]['com_title']);
                   for (i=0;i<a.length; i++){
                      console.log(a[0]['com_title']);
                   }
              }
              </script>
              </div>

上面的代码是我到目前为止所做的。如果执行，则可以获取数据。但我不知道如何从后端节点js到前端javascript获取数据。

Answer 1

尝试一下：

/**** 
cmd: node showChart.js
URLs: 
http://localhost:3005
****/

const fs = require('fs');
var express = require('express');
var app = express();
var path = require('path');
var Chart = require('chart.js');
var result =[3,6,9];

app.get('/', function(req, res){
    let _resLine = '<h1>Ereignisse: ' + result+'</h1>';
    console.log('show chart:');
    console.log(_resLine);

    _html = "<script src='https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.5.0/Chart.min.js'></script>"+
    "<canvas id='bar-chart' width='800' height='450'></canvas>"+
    "<script>"+
    "var logChart = new Chart(document.getElementById('bar-chart'), {"+
    "type: 'horizontalBar',"+
    "data: {"+
      "labels: ['Ereignis1', 'Ereignis2', 'Ereignis3'],"+
      "datasets: ["+
        "{"+
          "label: 'Aufrufe',"+
          "backgroundColor: ['#3e95cd', '#8e5ea2','#3cba9f'],"+
          "data: ["+result[0]+","+result[1]+","+result[2]+"]"+
        "}"+
      "]"+
      "},"+
    "options: {"+
      "legend: { display: false },"+
      "title: {"+
        "display: true,"+
        "text: 'Ereignisse '"+
      "}"+
    "}"+
    "});"+
    "</script>";

    res.send(_html);
});

app.listen(3005);

Answer 2

我们在这里缺少上下文。

如果a是您的数据，并且您可以从此模板访问它，我想您可以执行以下操作：

                   data: {
                   labels: ['Morning', 'Afternoon', 'Night'],
                   datasets: [{
                       label: 'My First dataset',
                       backgroundColor: 'rgb(255, 99, 132)',
                       borderColor: 'rgb(255, 99, 132)',
                       data: a
                   }]
               }