The browser fails to display the canvas when using the fillRect function

As a novice in Canvas, I've been experimenting with some code, but unfortunately, it's not working for me. Here's the code I used. Can someone help me identify the issue?

<!DOCTYPE html>
<html>
<head>
  <title> 28 - Canvas - Create Simple Canvas </title>
  <meta charset="utf-8">
  <meta name="description" content="Canvas - Create Simple Canvas" >
  <style>
    canvas{
      width: 800px;
      height: 400px;
      border: 1px solid #ccc;
      margin: 50px auto;
      display: block;
    }
  </style>
</head>
<body>

  <canvas id="c">  </canvas>
  <script>

  var MyCanvas = document.getElementById('c');

  myContext = MyCanvas.getContext('2d');
  myContext.fillStyle = '#080';
  myContext.fillRect('0, 0, 100, 50');

    </script>

</body>
</html>

The console is showing me this error message: Uncaught TypeError: Failed to execute 'fillRect' on 'CanvasRenderingContext2D': 4 arguments required, but only 1 present.

Answer №1

If you launch your HTML file in Chrome and then access Chrome Developer tools (F12 on Windows) it will assist you in debugging your application. The console section in the developer tools will display any JavaScript errors on the screen and guide you to the location of the code error. For instance, when analyzing the code provided, I encountered the following error message:

Uncaught TypeError: Failed to execute 'fillRect' on 'CanvasRenderingContext2D': 4 arguments required, but only 1 present.
    at index.html: 26

Upon examining this error, I realized that the fillRect method was being passed arguments as strings. By referring to fillRect on MDN, it became clear that the method expects 4 numerical arguments, as indicated in the error message. Therefore, I modified line 26 from

myContext.fillRect('0, 0, 100, 50');
to
myContext.fillRect(0, 0, 100, 50);
, removing the quotation marks, and the issue was resolved.

Adhering to this approach will aid in the debugging process of your code.

Answer №2

the fillRect function parameter should not be a string.

To set the values correctly, follow the example code below.

Change the line from

make myContext.fillRect('0, 0, 100, 50'); to

myContext.fillRect(0, 0, 100, 50);

<!DOCTYPE html>
<html>
<head>
  <title> 28 - Canvas - Create Simple Canvas </title>
  <meta charset="utf-8">
  <meta name="description" content="Canvas - Create Simple Canvas" >
  <style>
    canvas{
      width: 800px;
      height: 400px;
      border: 1px solid #ccc;
      margin: 50px auto;
      display: block;
    }
  </style>
</head>
<body>

  <canvas id="c"> </canvas>
  <script>

  var MyCanvas = document.getElementById('c');

  myContext = MyCanvas.getContext('2d');
  myContext.fillStyle = '#080';
  myContext.fillRect(0, 0, 100, 50);

  </script>

</body>
</html>

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