A canvas lineWidth example

function canvasReady() {
  draw(document.getElementById('canvas').getContext('2d'));
}
function draw(ctx) {
  for (var i=0;i<10;i++){
    ctx.lineWidth = 1+i;
    ctx.beginPath();
    ctx.moveTo(5+i*14,5);
    ctx.lineTo(5+i*14,140);
    ctx.stroke();
  }
}