创建画布并根据选择切换图像

<canvas id="myCanvas" width="500" height="500"></canvas>

var canvas = document.getElementById("myCanvas");
var ctx = canvas.getContext("2d");

var image1 = new Image();
image1.src = "image1.jpg";
var image2 = new Image();
image2.src = "image2.jpg";

// 监听选择切换事件
var selectElement = document.getElementById("imageSelector");
selectElement.addEventListener("change", function() {
  var selectedValue = selectElement.options[selectElement.selectedIndex].value;
  if (selectedValue === "image1") {
    ctx.drawImage(image1, 0, 0);
  } else if (selectedValue === "image2") {
    ctx.drawImage(image2, 0, 0);
  }
});