Where is the canvas javascript code written?-Front-end Q&A-php.cn

Where is the canvas javascript code written?

PHPz

Release： 2023-04-25 10:02:46

Original

434 people have browsed it

Canvas is a new feature of HTML5, which can be used for drawing operations through JavaScript. So, where should we write the canvas-related JavaScript code?

Generally speaking, canvas-related JavaScript code should be written in the <script></script> tag of the HTML file, or referenced in a separate JavaScript file. Specifically, this can be achieved through the following steps:

Create HTML file: First, we need to create an HTML file, which can be created through a text editor or IDE and other tools. The specific code is as follows:

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <title>画布JavaScript代码示例</title>
  </head>

  <body>
    <canvas id="myCanvas"></canvas>

    <script src="js/canvas.js"></script>
  </body>
</html>

Copy after login

This is a simple HTML file, which contains a <canvas> tag and a <script> tag. The <canvas> tag is used to display the canvas, and the <script> tag is used to reference the JavaScript file.

Create JavaScript file: In the above HTML file, we referenced a JavaScript file named canvas.js. Therefore, we need to create the canvas.js file in the project and write the canvas-related code in it. The specific code examples are as follows:

// 获取canvas元素
let canvas = document.getElementById('myCanvas');

// 获取canvas上下文
let ctx = canvas.getContext('2d');

// 绘制矩形
ctx.fillStyle = 'orange';
ctx.fillRect(10, 10, 100, 50);

// 绘制圆形
ctx.fillStyle = 'green';
ctx.beginPath();
ctx.arc(150, 35, 25, 0, 2 * Math.PI);
ctx.fill();

// 绘制文本
ctx.fillStyle = 'blue';
ctx.font = '20px Arial';
ctx.fillText('Hello World!', 200, 35);

Copy after login

The above code is used to draw an orange rectangle, a green circle and a blue text. Among them, the getContext() method is used to obtain the canvas context, and drawing operations can be performed through the context object.

Reference the JavaScript file in the HTML file: After the above two steps are completed, we need to reference the JavaScript file written in step 2 into the HTML file. The specific code is as follows:

<script src="js/canvas.js"></script>

Copy after login

After adding the above code to the HTML file, the browser can load and execute the JavaScript code in the canvas.js file to realize the canvas drawing function. .

In short, for canvas-related JavaScript code, we can reference it through the <script> tag or a separate JavaScript file to achieve canvas drawing. Correctly referencing JavaScript files is one of the keys to ensuring the normal operation of JavaScript code.

The above is the detailed content of Where is the canvas javascript code written?. For more information, please follow other related articles on the PHP Chinese website!