Check out example codes for "canvas html". It will help you in understanding the concepts better.
Code Example 1
<canvas id="myCanvas" width="200" height="100"></canvas>
Code Example 2
#this code creates a circle within a canvas that must be created in HTML
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.arc(95, 50, 40, 0, 2 * Math.PI);
ctx.stroke();
Code Example 3
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.moveTo(0, 0);
ctx.lineTo(200, 100);
ctx.stroke();
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