canvas in HTML5 and creating multiple circles -


following w3c school explanation of canvas, understand creating shapes...

<script>   var canvas = document.getelementbyid('mycanvas');   var context = canvas.getcontext('2d');   var centerx = canvas.width / 2;   var centery = canvas.height / 2;   var radius = 20;    context.beginpath();   context.arc(centerx, centery, radius, 0, 2 * math.pi, false);   context.fillstyle = 'green';   context.fill();   context.linewidth = 5;   context.strokestyle = '#003300';   context.stroke(); </script>

this make green circle canvas is.

<canvas id="mycanvas"></canvas>

however - want apply "circle" multiple places on page, , doing id ridiculous.

how 1 apply context (as defined above) multiple canvas'?? i' assume using class, seems logical way.

<canvas class="reddot"></canvas> <canvas class="reddot"></canvas> <canvas class="reddot"></canvas>  <canvas class="greendot"></canvas> <canvas class="greendot"></canvas>  <canvas class="bluedot"></canvas> <canvas class="bluedot"></canvas> <canvas class="bluedot"></canvas>

you have iterate through each element apply changes. i.e:

var dots = document.getelementsbyclassname('dots'); (var i=0;i<dots.length;i++){     var canvas = dots[i];     var context = canvas.getcontext('2d');     // draw circles here  }

ideally, have 1 canvas element can draw multiple circles

var canvas = document.getelementbyid('myoneandonlycanvas'); // using css , layering can make background var context = canvas.getcontext('2d');  dot('red',50,50); dot('blue',100,50); //etc..  function dot(color,x,y){   context.beginpath();   context.arc(y, y, radius, 0, 2 * math.pi, false);   context.fillstyle = color;   context.fill();   context.linewidth = 5;   context.strokestyle = '#003300';   context.stroke(); }

but if doesn't fit use case using svg object?

since mentioned w3 schools: http://www.w3schools.com/svg/ ideally check out: http://www.w3.org/graphics/svg/

mind, dom heavy pages can hurt load times. depending on want might wiser use image (eg. large cluster of dots).


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