Canvas reference: The lineCap property

The lineCap property is used to set how the ends of lines are drawn

The lineCap property is used to change the way that the ends of lines are drawn. The possible values are butt (default), round and square. Examples of these are shown below. Although the butt and square settings appear to be the same you should note that the square setting has overhang whilst the butt setting does not.

An example

<script>
    window.onload = function ()
    {
        var canvas  = document.getElementById("cvs");
        var context = canvas.getContext('2d');
        
        // Translate by half a pixel - this makes lines look crisp
        context.translate(0.5, 0.5);
            
        context.beginPath();
        context.lineCap = 'butt';
        context.lineWidth = 25;
        context.moveTo(25,100);
        context.lineTo(175,100);
        context.stroke();
    }
</script>