这是一段使用 moveTo 方法的简单的代码片段，移动画笔到起始点绘制一条线。
HTML
<canvas id="canvas"></canvas>
JavaScript
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
ctx.beginPath();
ctx.moveTo(50,50);
ctx.lineTo(200, 50);
ctx.stroke();
修改下面的代码并在线查看 canvas 的变化：
<canvas id="canvas" width="400" height="200" class="playable-canvas"></canvas>
<div class="playable-buttons">
<input id="edit" type="button" value="Edit" />
<input id="reset" type="button" value="Reset" />
</div>
<textarea id="code" class="playable-code">
ctx.beginPath();
ctx.moveTo(50,50);
ctx.lineTo(200, 50);
ctx.stroke()</textarea>
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var textarea = document.getElementById("code");
var reset = document.getElementById("reset");
var edit = document.getElementById("edit");
var code = textarea.value;
function drawCanvas() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
eval(textarea.value);
}
reset.addEventListener("click", function() {
textarea.value = code;
drawCanvas();
});
edit.addEventListener("click", function() {
textarea.focus();
})
textarea.addEventListener("input", drawCanvas);
window.addEventListener("load", drawCanvas);