如果你只使用clearRect，如果你在一个表单中提交你的图纸，你会得到一个提交而不是清除，或者可能它可以先清除，然后上传一个无效的图纸，所以你需要在函数的开头添加一个preventDefault:

   function clearCanvas(canvas,ctx) {
        event.preventDefault();
        ctx.clearRect(0, 0, canvas.width, canvas.height);
    }


<input type="button" value="Clear Sketchpad" id="clearbutton" onclick="clearCanvas(canvas,ctx);">

希望它能帮助到别人。

如果你在画线条，请确保不要忘记:

context.beginPath();

否则这些行就不会被清除。

Chrome响应良好:上下文。clearRect (x, y, w, h);正如@Pentium10所建议的，但IE9似乎完全忽略了这条指令。 IE9似乎对:canvas做出了响应。宽度= canvas.width;但它不清除线条，只是形状，图片和其他物体，除非你也使用@John Allsopp的解决方案，首先改变宽度。

如果你有一个canvas和context是这样创建的:

var canvas = document.getElementById('my-canvas');
var context = canvas.getContext('2d');

你可以使用这样的方法:

function clearCanvas(context, canvas) {
  context.clearRect(0, 0, canvas.width, canvas.height);
  var w = canvas.width;
  canvas.width = 1;
  canvas.width = w;
}

使用clearRect方法通过传递x,y坐标和画布的高度和宽度。ClearRect将清除整个画布:

canvas = document.getElementById("canvas");
ctx = canvas.getContext("2d");
ctx.clearRect(0, 0, canvas.width, canvas.height);

This is a Free hand drawing Canvas with a Clear Canvas Button. See this live example of a canvas which you can draw on and also when required clear it for redrawing clearRect() is used to delete the prersent canvas and fillRect() is used to again draw the initial canvas which was clean and had no drawings on it. var canvas = document.getElementById("canvas"), ctx = canvas.getContext("2d"), painting = false, lastX = 0, lastY = 0, lineThickness = 1; canvas.width=canvas.height = 250; ctx.fillRect(0, 0, 250, 250); canvas.onmousedown = function(e) { painting = true; ctx.fillStyle = "#ffffff"; lastX = e.pageX - this.offsetLeft; lastY = e.pageY - this.offsetTop; }; canvas.onmouseup = function(e){ painting = false; } canvas.onmousemove = function(e) { if (painting) { mouseX = e.pageX - this.offsetLeft; mouseY = e.pageY - this.offsetTop; // find all points between var x1 = mouseX, x2 = lastX, y1 = mouseY, y2 = lastY; var steep = (Math.abs(y2 - y1) > Math.abs(x2 - x1)); if (steep){ var x = x1; x1 = y1; y1 = x; var y = y2; y2 = x2; x2 = y; } if (x1 > x2) { var x = x1; x1 = x2; x2 = x; var y = y1; y1 = y2; y2 = y; } var dx = x2 - x1, dy = Math.abs(y2 - y1), error = 0, de = dy / dx, yStep = -1, y = y1; if (y1 < y2) { yStep = 1; } lineThickness = 4; for (var x = x1; x < x2; x++) { if (steep) { ctx.fillRect(y, x, lineThickness , lineThickness ); } else { ctx.fillRect(x, y, lineThickness , lineThickness ); } error += de; if (error >= 0.5) { y += yStep; error -= 1.0; } } lastX = mouseX; lastY = mouseY; } } var button=document.getElementById("clear"); button.onclick=function clearcanvas(){ canvas=document.getElementById("canvas"), ctx = canvas.getContext('2d'); ctx.clearRect(0, 0, 250, 250); canvas.width=canvas.height = 250; ctx.fillRect(0, 0, 250, 250);} #clear{border-radius:10px; font-size:8px !important; position:absolute; top:1px;} #canvas{border-radius:10px} <link href="https://www.w3schools.com/w3css/4/w3.css" rel="stylesheet"/> <button id="clear" class="w3-padding w3-xxlarge w3-pink" type="button">Clear Canvas</button> <canvas id="canvas"></canvas>

我总是用

ctx.fillStyle = "rgb(255, 255, 255)";
ctx.fillRect(0, 0, canvas.width, canvas.height);

对于自定义颜色，和

ctx.clearRect(0, 0, canvas.width, canvas.height);

用于使画布透明时清除