Canvas in JS - smallQuerty/canvas_charts GitHub Wiki
A canvas is a rectangular area on an HTML page. By default, a canvas has no border and no content.
in html file you must always create specific canvas for work
<canvas id="myCanvas" width="200" height="100"></canvas>
Note: Always specify an id attribute (to be referred to in a script), and a width and height attribute to define the size of the canvas. To add a border, use the style attribute.
After creating the rectangular canvas area, you must add a JavaScript to do the drawing. Expale for calling your canvas:
<script>
let content=document.getElementById("canvas").getContext("2d");
</script>