CodePen Embed - 透明度

<canvas id="canvas" width="200px" height="200px"></canvas>

#canvas {
  border: 1px solid #ccc
}

const canvas = document.getElementById("canvas");
const cxt = canvas.getContext("2d");
cxt.globalAlpha = 0.2;
for (let i = 1; i < 5; i++ ) {
  cxt.beginPath();
  cxt.arc( i * 30,  i * 30, 20, 0, 7, false);
  cxt.fillStyle = "#db3edc";
  cxt.fill();
}

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