CODEWITHSUNDEEP
javascriptcolorsrectangles
Kait Jardine
Kait Jardine

Reputation: 103

Javascript color rectangle array

I'm trying to use a pair of for loops generate a 4 by 4 array of 16 small rectangles each with a different color. However, the colors are not changing.

  var x;
  var y;
  var color;
  for (x=0; x < 4; x++){
    for (y=0; y < 4; y++){
      color = 255 - x*20 - y*20;
      ctx.fillStyle = 'rgba(0, 0, color, 1.0)'; 
      ctx.fillRect((x*10), (y*10), 10, 10);
    }
  }

Upvotes: 0

Views: 464

Answers (2)

epascarello
epascarello

Reputation: 207557

You are setting it to the string color, not the variable. You need to fix how you are building the string.

var c=document.getElementById("myCanvas");
var ctx=c.getContext("2d");


var x;
var y;
var color;
for (x = 0; x < 4; x++) {
  for (y = 0; y < 4; y++) {
    color = 255 - x * 20 - y * 20;
    ctx.fillStyle = 'rgba(0, 0, ' + color + ', 1.0)'; 
    ctx.fillRect((x*10), (y*10), 10, 10);
  }
}
<canvas id="myCanvas" width="300" height="150" style="border:1px solid #d3d3d3;">

Upvotes: 4

Baboo
Baboo

Reputation: 4278

color is a string in the string you provide to fillStyle, not the value of the variable color. Here is the fixed version:

  var x;
  var y;
  var color;
  for (x=0; x < 4; x++){
    for (y=0; y < 4; y++){
      color = 255 - x*20 - y*20;
      ctx.fillStyle = 'rgba(0, 0, ' + color + ', 1.0)';  // Here
      ctx.fillRect((x*10), (y*10), 10, 10);
    }
  }

Upvotes: 1

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