Element: mouseup event

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范例
规范
浏览器兼容性
另请参阅
相关话题

mouseup event is fired at an 元素 when a button on a pointing device (such as a mouse or trackpad) is released while the pointer is located inside it. mouseup events are the counterpoint to mousedown 事件。

冒泡	Yes
可取消	Yes
接口	`MouseEvent`
事件处理程序特性	`onmouseup`

范例

以下范例使用 mousedown , mousemove ，和 mouseup events to allow the user to draw on an HTML5 canvas . Its functionality is simple: the thickness of the line is set to 1, and the color is always black.

When the page loads, constants myPics and context are created to store a reference to the canvas and the 2d context we will use to draw.

Drawing begins when the mousedown event fires. First we store the x and y coordinates of the mouse pointer in the variables x and y , and then set isDrawing to true.

As the mouse moves over the page, the mousemove event fires. If isDrawing is true, the event handler calls the drawLine function to draw a line from the stored x and y values to the current location.

当 drawLine() function returns, we adjust the coordinates and then save them in x and y .

mouseup event draws the final line segment, sets x and y to 0 , and stops further drawing by setting isDrawing to false .

HTML

<h1>Drawing with mouse events</h1>
<canvas id="myPics" width="560" height="360"></canvas>

CSS

canvas {
  border: 1px solid black;
  width: 560px;
  height: 360px;
}

JavaScript

// When true, moving the mouse draws on the canvas
let isDrawing = false;
let x = 0;
let y = 0;
const myPics = document.getElementById('myPics');
const context = myPics.getContext('2d');
// event.offsetX, event.offsetY gives the (x,y) offset from the edge of the canvas.
// Add the event listeners for mousedown, mousemove, and mouseup
myPics.addEventListener('mousedown', e => {
  x = e.offsetX;
  y = e.offsetY;
  isDrawing = true;
});
myPics.addEventListener('mousemove', e => {
  if (isDrawing === true) {
    drawLine(context, x, y, e.offsetX, e.offsetY);
    x = e.offsetX;
    y = e.offsetY;
  }
});
window.addEventListener('mouseup', e => {
  if (isDrawing === true) {
    drawLine(context, x, y, e.offsetX, e.offsetY);
    x = 0;
    y = 0;
    isDrawing = false;
  }
});
function drawLine(context, x1, y1, x2, y2) {
  context.beginPath();
  context.strokeStyle = 'black';
  context.lineWidth = 1;
  context.moveTo(x1, y1);
  context.lineTo(x2, y2);
  context.stroke();
  context.closePath();
}

结果

规范

规范	状态
UI Events The definition of 'mouseup' in that specification.	工作草案
DOM (文档对象模型) 3 级事件规范 The definition of 'mouseup' in that specification.	过时

浏览器兼容性

更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`mouseup` event	Chrome 2	Edge 12	Firefox 6	IE 9	Opera 11.6	Safari 4	WebView Android ≤37	Chrome Android 18	Firefox Android 6	Opera Android 12.1	Safari iOS 3.2	Samsung Internet Android 1.0

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范例

HTML

CSS

JavaScript

结果

规范

浏览器兼容性

图例

另请参阅

元数据

相关话题