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I'm having trouble trying to figure out how to center the canvas in the page. The canvas's code is in a javascript file. Here's the html for the page.

<!DOCTYPE html>
<html>
   <head>
       <meta charset="utf-8">
       <title>Game Tut</title>
   </head>
   <body>

       <script src="game.js"></script>
   </body>
 </html>

I've tried something like this in the javascript file.

var canvas = document.createElement("canvas");
canvas.width = 800;
canvas.height = 600;
canvas.tabindex = 0;
canvas.style = "position: absolute; top: 50px; left: 50px; border:2px solid blue"
document.addEventListener('keydown', doKeyDown, true);
var ctx = canvas.getContext("2d");
document.body.appendChild(canvas);

For some reason the blue border or the positioning don't seem to show up in Google Chrome.

I'm having trouble trying to figure out how to center the canvas in the page. The canvas's code is in a javascript file. Here's the html for the page.

<!DOCTYPE html>
<html>
   <head>
       <meta charset="utf-8">
       <title>Game Tut</title>
   </head>
   <body>

       <script src="game.js"></script>
   </body>
 </html>

I've tried something like this in the javascript file.

var canvas = document.createElement("canvas");
canvas.width = 800;
canvas.height = 600;
canvas.tabindex = 0;
canvas.style = "position: absolute; top: 50px; left: 50px; border:2px solid blue"
document.addEventListener('keydown', doKeyDown, true);
var ctx = canvas.getContext("2d");
document.body.appendChild(canvas);

For some reason the blue border or the positioning don't seem to show up in Google Chrome.

  • javascript
  • html
  • canvas
Share Improve this question asked Nov 12, 2013 at 5:04 JalepanoJalepano 511 gold badge1 silver badge4 bronze badges
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3 Answers 3

Reset to default 3

Try this

the code below made the canvas center

canvas.style = "position: absolute; top: 0px; left: 0px; right: 0px; bottom: 0px; margin: auto; border:2px solid blue";

By the way

document.addEventListener('keydown', doKeyDown, true);

I posted your code but chrome showed the 'doKeyDown' function is undefined so maybe you need to fix this error then your canvas will show correctly.

Error showed

var canvas = document.getElementsByName("canvas")[0];
var style = canvas.style;
style.marginLeft = "auto";
style.marginRight = "auto";
var parentStyle = canvas.parentElement.style;
parentStyle.textAlign = "center";
parentStyle.width = "100%";

OR

canvas.style = "position:absolute; left: 50%; width: 400px; margin-left: -200px;";

Try this:

var canvas = document.createElement("canvas");
canvas.width = 800;
canvas.height = 600;
canvas.tabindex = 0;
canvas.setAttribute('style', "position: absolute;  left: 50%;margin-left:-400px; top: 50%;margin-top:-300px; border:2px solid blue");
var ctx = canvas.getContext("2d");
document.body.appendChild(canvas);
document.addEventListener('keydown', doKeyDown, true);

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