JavaScript: Draw two intersecting rectangles, one of which has alpha transparency

Last update on May 30 2022 09:59:41 (UTC/GMT +8 hours)

JavaScript Drawing: Exercise-3 with Solution

Write a JavaScript program to draw two intersecting rectangles, one of which has alpha transparency.

Sample output :

Sample Solution:

HTML Code:

<!DOCTYPE html>
  <html>
  <head>
  <meta charset=utf-8 />
  <title>Draw two intersecting rectangles, one of which has alpha transparency</title>
  </head>
  <body onload="draw();">
  <canvas id="canvas" width="150" height="150"></canvas>
  </body>
  </html>

JavaScript Code:

function draw() 
  {
      var canvas = document.getElementById("canvas");
      if (canvas.getContext)
      {
        var context = canvas.getContext("2d");

        context.fillStyle = "rgb(256,0,0)";
        context.fillRect (15, 10, 55, 50);
        
        context.fillStyle = "rgba(0, 0, 200, 0.6)";
        context.fillRect (35, 30, 55, 50);
      }
  }

Live Demo:

See the Pen javascript-drawing-exercise-3 by w3resource (@w3resource) on CodePen.

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JavaScript: Tips of the Day

How to insert an item into an array at a specific index (JavaScript)?

What you want is the splice function on the native array object.

arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:

var arr = [];
arr[0] = "Jani";
arr[1] = "Hege";
arr[2] = "Stale";
arr[3] = "Kai Jim";
arr[4] = "Borge";

console.log(arr.join());
arr.splice(2, 0, "Lene");
console.log(arr.join());

Ref: https://bit.ly/2BXbp04