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/*
* Instances of SmartInterval extend the functionality of `setInterval`, make it configurable
* and controllable by a public API.
*
* */
(() => {
class SmartInterval {
/**
* @param { function } callback Function to be called on each iteration (required)
* @param { milliseconds } startingInterval `currentInterval` is set to this initially
* @param { milliseconds } maxInterval `currentInterval` will be incremented to this
* @param { integer } incrementByFactorOf `currentInterval` is incremented by this factor
* @param { boolean } lazyStart Configure if timer is initialized on instantiation or lazily
*/
constructor({ callback, startingInterval, maxInterval, incrementByFactorOf, lazyStart }) {
this.cfg = {
callback,
startingInterval,
maxInterval,
incrementByFactorOf,
lazyStart,
};
this.state = {
intervalId: null,
currentInterval: startingInterval,
pageVisibility: 'visible',
};
this.initInterval();
}
/* public */
start() {
const cfg = this.cfg;
const state = this.state;
state.intervalId = window.setInterval(() => {
cfg.callback();
if (this.getCurrentInterval() === cfg.maxInterval) {
return;
}
this.incrementInterval();
this.resume();
}, this.getCurrentInterval());
}
// cancel the existing timer, setting the currentInterval back to startingInterval
cancel() {
this.setCurrentInterval(this.cfg.startingInterval);
this.stopTimer();
}
// start a timer, using the existing interval
resume() {
this.stopTimer(); // stop exsiting timer, in case timer was not previously stopped
this.start();
}
destroy() {
this.cancel();
$(document).off('visibilitychange').off('page:before-unload');
}
/* private */
initInterval() {
const cfg = this.cfg;
if (!cfg.lazyStart) {
this.start();
}
this.initVisibilityChangeHandling();
this.initPageUnloadHandling();
}
initVisibilityChangeHandling() {
// cancel interval when tab no longer shown (prevents cached pages from polling)
$(document)
.off('visibilitychange').on('visibilitychange', (e) => {
this.state.pageVisibility = e.target.visibilityState;
this.handleVisibilityChange();
});
}
initPageUnloadHandling() {
// prevent interval continuing after page change, when kept in cache by Turbolinks
$(document).on('page:before-unload', () => this.cancel());
}
handleVisibilityChange() {
const state = this.state;
const intervalAction = state.pageVisibility === 'hidden' ? this.cancel : this.resume;
intervalAction.apply(this);
}
getCurrentInterval() {
return this.state.currentInterval;
}
setCurrentInterval(newInterval) {
this.state.currentInterval = newInterval;
}
incrementInterval() {
const cfg = this.cfg;
const currentInterval = this.getCurrentInterval();
let nextInterval = currentInterval * cfg.incrementByFactorOf;
if (nextInterval > cfg.maxInterval) {
nextInterval = cfg.maxInterval;
}
this.setCurrentInterval(nextInterval);
}
stopTimer() {
const state = this.state;
state.intervalId = window.clearInterval(state.intervalId);
}
}
gl.SmartInterval = SmartInterval;
})(window.gl || (window.gl = {}));
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