浅谈在react中如何实现扫码输入

let code = '';
let lastTime,
 nextTime,
 lastCode,
 nextCode;


function scanEvent(e, cb) {
 nextCode = e.which;
 nextTime = new Date().getTime();

 if (lastCode != null && lastTime != null && nextTime - lastTime <= 30) {
 code += String.fromCharCode(lastCode);
 } else if (lastCode != null && lastTime != null && nextTime - lastTime > 100) {
 code = '';
 }

 lastCode = nextCode;
 lastTime = nextTime;
 if (e.which === 13) {
 cb(code);
 console.log('code', code);
 code = '';
 }
}

export { scanEvent };

class Sample extends React.Component{
 componentDidMount(){
 window.addEventListener('keypress', this.scanWrapper, false);
 }

 componentWillUnmount() {
 window.removeEventListener('keypress', this.scanWrapper, false);
 }

 scanWrapper(e) {
 scanEvent(e, (code) => {
 // to do something...
 });
 }
}