timeout cancellation javascript program

Author: jeffersonbalde

TimeoutCancellation.js

@@ -0,0 +1,50 @@
+// 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.
+
+/**
+ * @param {Function} fn
+ * @param {Array} args
+ * @param {number} t
+ * @return {Function}
+ */
+var cancellable = function(fn, args, t) {
+    const timeoutId = setTimeout(function() {
+      fn.apply(null, args);
+    }, t);
+  
+    const cancelFn = function() {
+      clearTimeout(timeoutId);
+    };
+  
+    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)
+   */