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

JavaScript Drawing: Exercise-3 with Solution

Write a JavaScript program to draw two intersecting rectangles, one with Alpha transparency.

Sample output :

intersecting rectangles

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

Log the values that are commented out after the console.log statement

function* startGame() {
  const answer = yield 'Do you love JavaScript?';
  if (answer !== 'Yes') {
    return "Oh wow... Guess we're gone here";
  }
  return 'JavaScript loves you back ?';
}

const game = startGame();
console.log(/* 1 */); // Do you love JavaScript?
console.log(/* 2 */); // JavaScript loves you back ?

A generator function "pauses" its execution when it sees the yield keyword. First, we have to let the function yield the string "Do you love JavaScript?", which can be done by calling game.next().value.
Every line is executed, until it finds the first yield keyword. There is a yield keyword on the first line within the function: the execution stops with the first yield! This means that the variable answer is not defined yet!
When we call game.next("Yes").value, the previous yield is replaced with the value of the parameters passed to the next() function, "Yes" in this case. The value of the variable answer is now equal to "Yes". The condition of the if-statement returns false, and JavaScript loves you back ? gets logged.

Ref: https://bit.ly/3jFRBje

 

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