使用ExpressJS+Handlebars+MongoDB时无法渲染Morris.js图表求助

Hey there! Let's walk through the most common issues that might be stopping your Morris.js chart from rendering properly. I've dealt with this exact stack before, so here's what to check:

1. Double-check your dependency load order #

Morris.js relies on jQuery and Raphael to work—if these aren't loaded before Morris.js, you'll get a "Morris is not defined" error (check your browser console for this!). Make sure your script tags in index.hbs follow this exact order:

<!-- First jQuery -->
<script src="https://code.jquery.com/jquery-3.6.4.min.js"></script>
<!-- Then Raphael -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/raphael/2.3.0/raphael.min.js"></script>
<!-- Then Morris.js + its CSS -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/morris.js/0.5.1/morris.min.js"></script>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/morris.js/0.5.1/morris.css">

Pro tip: Put these in your <head> or right before the closing </body> tag—just make sure they load before your chart initialization code.

2. Fix Handlebars data escaping #

Handlebars automatically escapes HTML/JSON by default, which means {{graph}} will turn your data array into an escaped string that Morris can't parse. You have two easy fixes here:

• Option 1: Use triple curly braces in your template to skip escaping:

  data: {{{graph}}},
  

• Option 2: Stringify your data in your Express route before passing it to Handlebars:

  // In your Express route handler
  const chartData = [
    { month: 'Jan', sales: 100 },
    { month: 'Feb', sales: 150 },
    // ... more data
  ];
  res.render('index', { graph: JSON.stringify(chartData) });
  

Also, make sure your data matches Morris's required format—each object needs an x-axis key (like month above) and corresponding y-axis values. Don't forget to define xkey and ykeys in your Morris config!

3. Ensure your DOM element exists #

Morris needs a target element to render into—double-check that you have a <div> with the ID myfirstchart in your page, and that it's present before your chart code runs:

<!-- Put this somewhere in your index.hbs body -->
<div id="myfirstchart" style="height: 300px;"></div>

If your template is being injected dynamically, wrap your Morris initialization in a DOM-ready callback to wait for the element to load:

<script id="entry-template" type="text/x-handlebars-template">
  $(document).ready(function() {
    console.log("fooooo")
    new Morris.Line({
      element: 'myfirstchart',
      data: {{{graph}}},
      xkey: 'month', // Match your data's x-axis field
      ykeys: ['sales'], // Match your data's y-axis fields
      labels: ['Monthly Sales'] // Legend labels
    });
  });
</script>

4. Check your browser console for errors #

This is the fastest way to pinpoint issues! Hit F12 to open DevTools, go to the Console tab, and look for:

• "Morris is not defined": Dependencies are missing/out of order
• "Cannot read property '...' of undefined": Data is malformed or missing required fields
• "Element not found": Your myfirstchart div doesn't exist or isn't loaded yet

5. Verify template rendering timing #

If you're compiling the Handlebars template client-side (instead of server-side rendering), make sure you initialize Morris after the template has been inserted into the DOM. For example:

// Client-side template compile example
const template = Handlebars.compile($('#entry-template').html());
const html = template({ graph: chartData });
$('#chart-container').html(html);
// Now initialize Morris here, after the template is rendered
new Morris.Line({ /* config */ });

Try these steps one by one—9 times out of 10, it's a dependency order or data escaping issue. Let me know if you hit a specific error in the console and I can help dig deeper!

内容的提问来源于stack exchange，提问作者Ben Mustapha Sabrine