Canvas
The canvas tag was introduced by Apple and has been standardized to become part of HTML5.
A example for color cycling with the canvas element [[1]]
Get the canvas tag:
c=document.getElementById("c")
Get the "context" (like a paper):
p=c.getContext("2d");
Draw something!
p.fillRect(0, 0, 100, 100);
Examples
Here is a complete HTML page with a working canvas:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<script>
function draw(){
c = document.getElementById("canvas")
//console.log("c is",c)
p = c.getContext("2d")
x = 10
while (x<300) {
p.strokeRect(x,100,20,40)
x+=60
}
}
</script>
</head>
<body onload="draw()">
<h1>Hello canvas</h1>
<canvas id="canvas" width="640" height="640" style="border: 3px dotted red"></canvas>
</body>
</html>
Here's the output:
<canvas id="c1" width="300" height="300"> function draw(){
c = document.getElementById("c1")
//console.log("c is",c)
p = c.getContext("2d")
x = 10
while (x<300) {
p.strokeRect(x,100,20,40)
x+=60
}
} </canvas>
Variation: When the loop reaches the end of page it breaks the line. It redefines the "x" value to the begin of the line and adds 40px to "y".
<canvas id="c2" width="300" height="300" showsrc="true"> function draw(){ c = document.getElementById("c2"); p = c.getContext("2d"); hands = 1; x = 20; y = 200;
while (hands < 100) { console.log(hands); p.strokeRect(x,y,20,20); x = x + 50; hands++; if (x > 600) { x = 20; y = y + 40; } } } </canvas>