如何在 javascript 中计算 y 时间内的 x 事件数？

Question

I have a class that receives an event, let's call it "EVENT_X".

It can receive this event many times over any amount of duration, but I need to know if it crosses a threshold lets say 10 "EVENT_X" events in 5 minutes, so I can take an action accordingly.

I am unable to figure out appropriate algorithm for this and also a one which will be efficient, I've just tried waiting till first 10 events come and checking if time is < 5, of course that doesn't solve the purpose.

Any help is much appreciated, thankyou!

Answer 1

Use a global array as stack for the date-objects when the button last have been clicked. Everytime it's clicked just another one is appended. If there at least 5 cut it on the last 5 and look for the difference from now to the first click in milliseconds. If it's smaller than 5000 than do what you want eg change the color of the button by adding a class or make output to the console.

Note: If you are to slow (more than 5s) than you have to click some more faster till the last 5 clicks in time. For demonstration I take only 5 clicks and 5 s, but you can easily change it to your desire.

 var counter = []; document.getElementById('btn').addEventListener('click', function() { let now = new Date(); counter.push(now); if (counter.length >=5) { counter = counter.slice(-5); let diff = now - counter[0]; if (diff <= 5000) { document.getElementById('btn').classList.add('x5'); console.log('Clicked 5x in the time.'); } } });

 .x5 { background: yellow; }

 <button id='btn'>Click it 5x</button>

Answer 2

So add an object and log when the event took place. When you add the event, filter out any events greater than 5 minutes. Check length. If hits the max, fire off whatever you were going to do next.

 const evtTypes = {}; function logEvent (event) { const { type } = event; evtTypes[type] = evtTypes[type] || []; evtTypes[type].push({ ts: new Date().getTime(), data: event }); evtTypes[type] = evtTypes[type].filter(({ ts }) => new Date().getTime() - ts < 300000); if (evtTypes[type].length >= 10) { console.log(`"${event.type}" triggered 10 times in 5 minutes.`); } } logEvent({ type: 'test', foo: 'bar01' }); logEvent({ type: 'test', foo: 'bar02' }); logEvent({ type: 'test', foo: 'bar03' }); logEvent({ type: 'test', foo: 'bar04' }); logEvent({ type: 'test', foo: 'bar05' }); logEvent({ type: 'test', foo: 'bar06' }); logEvent({ type: 'test', foo: 'bar07' }); logEvent({ type: 'test', foo: 'bar08' }); logEvent({ type: 'test', foo: 'bar09' }); logEvent({ type: 'test', foo: 'bar10' });