How to write a right triangle in JavaScript

JavaScript is a widely used scripting language used to achieve interactive and dynamic effects on web pages. In this language, we can easily draw various shapes and figures, including right triangles, with just a few lines of code.

The right triangle is a very basic geometric figure, consisting of a right angle and two acute angles. In this article, we will explore how to use JavaScript to write a program that can draw a right triangle.

First, let's learn how to use HTML and CSS to create a Canvas element, which is the container required for drawing.

HTML example:

<canvas id="myCanvas" width="500" height="500"></canvas>

CSS example:

canvas {
    border: 1px solid black;
}

The above HTML code creates a Canvas element with a black border and sets its width and height to 500 pixels. Next, we need to prepare some JavaScript code to draw a right triangle in this Canvas element.

First, we need to get this Canvas element in JavaScript:

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

Next, we need to get the context object of the Canvas element, which contains a series of graphics used to draw graphics. Method:

var ctx = canvas.getContext("2d");

Now, we can use the method on the ctx object to start drawing a right triangle.

ctx.beginPath(); // 开始路径
ctx.moveTo(100, 100); // 移动到起始位置
ctx.lineTo(100, 300); // 绘制垂直边
ctx.lineTo(300, 300); // 绘制水平边
ctx.closePath(); // 结束路径
ctx.stroke(); // 绘制轮廓线

In the above code, we start a new path by calling the ctx.beginPath() method, and then use the ctx.moveTo() method to move the path to the starting point Position (100,100), then use the ctx.lineTo() method to draw the two right-angled sides of the right triangle respectively, and finally call the ctx.closePath() method to end the path, and then use ctx.stroke()The method draws the outline of the path.

With the above code, we successfully drew a right triangle in the Canvas element. However, such drawing code is inconvenient when multiple right triangles need to be drawn. Therefore, we can encapsulate them into a function to call directly when needed.

function drawRightTriangle(x, y, width, height) {
    ctx.beginPath();
    ctx.moveTo(x, y);
    ctx.lineTo(x, y + height);
    ctx.lineTo(x + width, y + height);
    ctx.closePath();
    ctx.stroke();
}

In the above code, we define a function named drawRightTriangle, which accepts four parameters: x and y are the starting coordinates of the right triangle, width and height are the right angles The width and height of the triangle. This function is basically the same as the previous code, except that the code for drawing a right triangle is encapsulated into a function form. When calling this function, you only need to pass in the corresponding parameters to draw a right triangle with the corresponding position and size.

drawRightTriangle(50, 50, 100, 200);

Through the above method, we can easily write a program in JavaScript that can draw a right triangle, and realize the drawing of a right triangle with customizable position and size.

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