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2725. Interval Cancellation

Description

Given a function fn, an array of argumentsΒ args, andΒ an interval time t, return a cancel function cancelFn.

After a delay ofΒ cancelTimeMs, the returned cancel functionΒ cancelFnΒ will be invoked.

setTimeout(cancelFn, cancelTimeMs)

The function fn should be called with args immediately and then called again everyΒ t millisecondsΒ untilΒ cancelFnΒ is called at cancelTimeMs ms.

Β 

Example 1:

Input: fn = (x) => x * 2, args = [4], t = 35
Output: 
[
   {"time": 0, "returned": 8},
   {"time": 35, "returned": 8},
   {"time": 70, "returned": 8},
   {"time": 105, "returned": 8},
   {"time": 140, "returned": 8},
   {"time": 175, "returned": 8}
]
Explanation: 
const cancelTimeMs = 190;
const cancelFn = cancellable((x) => x * 2, [4], 35);
setTimeout(cancelFn, cancelTimeMs);

Every 35ms, fn(4) is called. Until t=190ms, then it is cancelled.
1st fn call is at 0ms. fn(4) returns 8.
2nd fn call is at 35ms. fn(4) returns 8.
3rd fn call is at 70ms. fn(4) returns 8.
4th fn call is atΒ 105ms. fn(4) returns 8.
5th fn call is at 140ms. fn(4) returns 8.
6th fn call is at 175ms. fn(4) returns 8.
Cancelled at 190ms

Example 2:

Input: fn = (x1, x2) => (x1 * x2), args = [2, 5], t = 30
Output: 
[
   {"time": 0, "returned": 10},
   {"time": 30, "returned": 10},
   {"time": 60, "returned": 10},
   {"time": 90, "returned": 10},
   {"time": 120, "returned": 10},
   {"time": 150, "returned": 10}
]
Explanation: 
const cancelTimeMs = 165; 
const cancelFn = cancellable((x1, x2) => (x1 * x2), [2, 5], 30) 
setTimeout(cancelFn, cancelTimeMs)

Every 30ms, fn(2, 5) is called. Until t=165ms, then it is cancelled.
1st fn call is at 0msΒ 
2nd fn call is at 30msΒ 
3rd fn call is at 60msΒ 
4th fn call is atΒ 90msΒ 
5th fn call is at 120msΒ 
6th fn call is at 150ms
Cancelled at 165ms

Example 3:

Input: fn = (x1, x2, x3) => (x1 + x2 + x3), args = [5, 1, 3], t = 50
Output: 
[
   {"time": 0, "returned": 9},
   {"time": 50, "returned": 9},
   {"time": 100, "returned": 9},
   {"time": 150, "returned": 9}
]
Explanation: 
const cancelTimeMs = 180;
const cancelFn = cancellable((x1, x2, x3) => (x1 + x2 + x3), [5, 1, 3], 50)
setTimeout(cancelFn, cancelTimeMs)

Every 50ms, fn(5, 1, 3) is called. Until t=180ms, then it is cancelled. 
1st fn call is at 0ms
2nd fn call is at 50ms
3rd fn call is at 100ms
4th fn call is atΒ 150ms
Cancelled at 180ms

Β 

Constraints:

  • fn is a function
  • args is a valid JSON array
  • 1 <= args.length <= 10
  • 30 <= t <= 100
  • 10 <= cancelTimeMs <= 500

Solutions

Solution 1

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function cancellable(fn: Function, args: any[], t: number): Function {
    fn(...args);
    const time = setInterval(() => fn(...args), t);
    return () => clearInterval(time);
}

/**
 *  const result = []
 *
 *  const fn = (x) => x * 2
 *  const args = [4], t = 20, cancelT = 110
 *
 *  const log = (...argsArr) => {
 *      result.push(fn(...argsArr))
 *  }
 *
 *  const cancel = cancellable(fn, args, t);
 *
 *  setTimeout(() => {
 *     cancel()
 *     console.log(result) // [
 *                         //      {"time":0,"returned":8},
 *                         //      {"time":20,"returned":8},
 *                         //      {"time":40,"returned":8},
 *                         //      {"time":60,"returned":8},
 *                         //      {"time":80,"returned":8},
 *                         //      {"time":100,"returned":8}
 *                         //  ]
 *  }, cancelT)
 */

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