how to draw a triangle using javascript

JavaScript
<!doctype html>
<html>
<head>
<body>
<canvas></canvas>
<script>
var canvas=document.querySelector('canvas');
var context=canvas.getContext(2d);
context.beginPath();
    context.moveTo(75,75);
    context.lineTo(10,75);
    context.lineTo(10,25);
    context.fill();
    </script>
    </body>
    </head>
    </html>
Source

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