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joplin/ReactNativeClient/lib/services/back-button.js
2017-11-03 00:13:17 +00:00

43 lines
936 B
JavaScript

const { BackHandler } = require('react-native');
class BackButtonService {
static initialize(defaultHandler) {
this.defaultHandler_ = defaultHandler;
BackHandler.addEventListener('hardwareBackPress', async () => {
return this.back();
});
}
static async back() {
if (this.handlers_.length) {
let r = await this.handlers_[this.handlers_.length - 1]();
if (r) return r;
}
return await this.defaultHandler_();
}
static addHandler(handler) {
for (let i = this.handlers_.length - 1; i >= 0; i--) {
const h = this.handlers_[i];
if (h === handler) return;
}
return this.handlers_.push(handler);
}
static removeHandler(hanlder) {
for (let i = this.handlers_.length - 1; i >= 0; i--) {
const h = this.handlers_[i];
if (h === hanlder) this.handlers_.splice(i, 1);
}
}
}
BackButtonService.defaultHandler_ = null;
BackButtonService.handlers_ = [];
module.exports = { BackButtonService };