react新增右鍵點選事件
1.在HTML裡面支援contextmenu事件(右鍵事件)。所以需要在組建載入完時新增此事件,銷燬組建時移除此事件。
2. 需要增加一個state,名稱為visible,用來控制選單是否顯示。在_handleContextMenu(右鍵事件)裡面,它被設定為true,從而可以顯示出來。那麼,當滑鼠點選其它位置或者滾動的時候,需要把 它設定為false。
例如程式碼:
class ContextMenu extends React.Component {
constructor(props) {
super(props);
this.state = {
visible: false,
};
}
componentDidMount() {
document.addEventListener('contextmenu', this._handleContextMenu);
document.addEventListener('click', this._handleClick);
document.addEventListener('scroll', this._handleScroll);
};
componentWillUnmount() {
document.removeEventListener('contextmenu', this._handleContextMenu);
document.removeEventListener('click', this._handleClick);
document.removeEventListener('scroll', this._handleScroll);
}
_handleContextMenu = (event) => {
event.preventDefault();
this.setState({ visible: true });
const clickX = event.clientX;
const clickY = event.clientY; //事件發生時滑鼠的Y座標
const screenW = window.innerWidth; //文件顯示區的寬度
const screenH = window.innerHeight;
const rootW = this.root.offsetWidth; //右鍵選單本身元素的寬度
const rootH = this.root.offsetHeight;
// right為true,說明滑鼠點選的位置到瀏覽器的右邊界的寬度可以放contextmenu。
// 否則,選單放到左邊。 // top和bottom,同理。
const right = (screenW - clickX) > rootW;
const left = !right;
const top = (screenH - clickY) > rootH;
const bottom = !top;
if (right) {
this.root.style.left = `${clickX + 15}px`;
}
if (left) {
this.root.style.left = `${clickX - rootW - 15}px`;
}
if (top) {
this.root.style.top = `${clickY + 15}px`;
}
if (bottom) {
this.root.style.top = `${clickY - rootH - 15}px`;
}
};
_handleClick = (event) => {
const { visible } = this.state;
const wasOutside = !(event.target.contains === this.root);
if (wasOutside && visible) this.setState({ visible: false, });
};
_handleScroll = () => {
const { visible } = this.state;
if (visible) this.setState({ visible: false, });
};
render() {
const { visible } = this.state;
return
{ visible?
<div ref={ref => {this.root = ref}} className="contextMenu">
<div>右鍵選單內容</div>
</div>: null}
};
}
ReactDOM.render(<ContextMenu />, document.getElementById('root'));