How to draw a square using javascript

Drawing a square using JavaScript is easy, you just need to know the regular drawing API. In the following article, we will explain how to draw a square using the JavaScript Canvas API.

Step 1: Create a canvas element

First, we need to create a canvas element in the HTML page to draw a square. We can use the following code:

<canvas id="myCanvas" width="200" height="200"></canvas>

Among them, the id parameter is used to uniquely identify the canvas element, and the width and height parameters are used to set the size of the canvas element.

Step 2: Get the canvas element

In JavaScript, we need to use the document.getElementById() method to get the canvas element. We can pass to this method based on the id parameter as follows:

const canvas = document.getElementById("myCanvas");

Now that we have obtained the canvas element, we must next draw using the canvas drawing context.

Step 3: Draw a square

We can draw a square by specifying the four points of the square. In order to draw a square, we need to specify the coordinates of the upper left and lower right corners. The following code can be used to draw a red square:

const ctx = canvas.getContext("2d");
ctx.beginPath();
ctx.fillStyle = "red";
ctx.fillRect(50, 50, 100, 100);

In this code, we first obtain the drawing context of the canvas. Next, we set the color of the square using the fill color (red). By starting at position 50, 50 and specifying a width and height of 100, we successfully created a 100x100 square.

Step 4: Implement interactivity

In order to increase interactivity, we can use the JavaScript AttachEvent method to bind mouse events to the canvas element. This way, when the user clicks on the canvas element, we can draw another square. The following is the complete implementation code:

const canvas = document.getElementById("myCanvas");
const ctx = canvas.getContext("2d");
canvas.addEventListener("click", handleClick);

function handleClick(event) {
  ctx.clearRect(0, 0, canvas.width, canvas.height);
  ctx.beginPath();
  ctx.fillStyle = "red";
  ctx.fillRect(50, 50, 100, 100);
  ctx.beginPath();
  ctx.fillStyle = "blue";
  ctx.fillRect(150, 150, 50, 50);
}

In this example, we set a click event listener for the canvas element. When the user clicks, we clear the canvas and draw the blue one at the new location. square.

Summary

In this article, we demonstrated how to draw a square using the Canvas API in JavaScript. Here we only cover some basic knowledge of drawing squares in JavaScript. In addition to this, there are other methods that can be used for drawing, such as paths, lines, shading, and more. However, once we understand the basics, other methods are not difficult to master. Next, you can move on to more complex drawing methods to enrich your HTML and JavaScript development experience.

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