solution0032.js

// 2715. Timeout Cancellation
// Given a function fn, an array of arguments args, and a timeout t in milliseconds, return a cancel function cancelFn.

// After a delay of t, fn should be called with args passed as parameters unless cancelFn was invoked before the delay of t milliseconds elapses, specifically at cancelT ms. In that case, fn should never be called.

 

// Example 1:

// Input: fn = (x) => x * 5, args = [2], t = 20, cancelT = 50
// Output: [{"time": 20, "returned": 10}]
// Explanation: 
// const cancel = cancellable((x) => x * 5, [2], 20); // fn(2) called at t=20ms
// setTimeout(cancel, 50);

// The cancellation was scheduled to occur after a delay of cancelT (50ms), which happened after the execution of fn(2) at 20ms.
// Example 2:

// Input: fn = (x) => x**2, args = [2], t = 100, cancelT = 50 
// Output: []
// Explanation: 
// const cancel = cancellable((x) => x**2, [2], 100); // fn(2) not called
// setTimeout(cancel, 50);

// The cancellation was scheduled to occur after a delay of cancelT (50ms), which happened before the execution of fn(2) at 100ms, resulting in fn(2) never being called.
// Example 3:

// Input: fn = (x1, x2) => x1 * x2, args = [2,4], t = 30, cancelT = 100
// Output: [{"time": 30, "returned": 8}]
// Explanation:
// const cancel = cancellable((x1, x2) => x1 * x2, [2,4], 30); // fn(2,4) called at t=30ms
// setTimeout(cancel, 100);

// The cancellation was scheduled to occur after a delay of cancelT (100ms), which happened after the execution of fn(2,4) at 30ms.
 

// Constraints:

// fn is a function
// args is a valid JSON array
// 1 <= args.length <= 10
// 20 <= t <= 1000
// 10 <= cancelT <= 1000



var cancellable = function(fn, args, t) {
    
    let timeout = setTimeout(()=> fn(...args), t)

    //cancel timeout
    let cancelfn = () => clearTimeout(timeout)

    return cancelfn
};


  const result = []
 
  const fn = (x) => x * 5
   const args = [2], t = 20, cancelT = 50
 
  const start = performance.now() 
 
   const log = (...argsArr) => {
       const diff = Math.floor(performance.now() - start);
       result.push({"time": diff, "returned": fn(...argsArr)})
   }
        
   const cancel = cancellable(log, args, t);
 
   const maxT = Math.max(t, cancelT)
            
   setTimeout(() => {
      cancel()
   }, cancelT)
 
   setTimeout(() => {
      console.log(result) // [{"time":20,"returned":10}]
   }, maxT + 15)