Select object from array at random

Question

I'm trying to make a function or an if condition that picks one of three circles every second randomly.

The context is that I want to make an animation and the circles should run from right canvas height/2 to left. Every second a new circle should drawn on the canvas but the other circles that were drawn before the new one shouldn't become deleted. How can I accomplish that?

var circle1={color: blue};
var circle2={color: yellow};
var circle3={color: orange};

var circles=[];
circles.push(circle1);
circles.push(circle2);
circles.push(circle3);

function drawCircle(circle){
      ctx.beginPath();
      ctx.arc(ballx * 108, canvasHeight / 2, x*5, 0, 2*Math.PI, false);
      ctx.fillStyle = 'circle.color';
      ctx.fill();

  }

Michael Laszlo · Accepted Answer · 2015-08-30 07:01:23Z

3

This function returns a random element from an array:

function getRandomElement(array) {
  if (array.length == 0) {
    return undefined;
  }
  return array[Math.floor(Math.random() * array.length)];
}

To see it in action, run this snippet:

function getRandomElement(array) {
  if (array.length == 0) {
    return undefined;
  }
  return array[Math.floor(Math.random() * array.length)];
}

var circles = [
  {color: 'yellow'},
  {color: 'orange'},
  {color: 'red'},
  {color: 'pink'},
  {color: 'blue'},
  {color: 'green'},
  {color: 'purple'},
  {color: 'brown'}
];

document.write('random circle: ' + JSON.stringify(getRandomElement(circles)));

answered Aug 30, 2015 at 7:01

Michael Laszlo

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