mouseup

当指针在元素中时, mouseup事件在指针设备(如鼠标或触摸板)按钮放开时触发。mouseup 事件与mousedown 事件相反。

Bubbles Yes
Cancelable Yes
Interface MouseEvent
Event handler property onmouseup

示例

The following example uses the mousedown, mousemove, and 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.

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

The 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();
}

Result

规范

规范 状态
UI Events
mouseup
Working Draft
Document Object Model (DOM) Level 3 Events Specification
mouseup
Obsolete

浏览器兼容性

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
mouseup eventChrome Full support 2Edge Full support 12Firefox Full support 6IE Full support 9Opera Full support 11.6Safari Full support 4WebView Android Full support ≤37Chrome Android Full support 18Firefox Android Full support 6Opera Android Full support 12.1Safari iOS Full support 3.2Samsung Internet Android Full support 1.0

Legend

Full support  
Full support

参见