Master the Art of Function Intervals with Easy Cancellation – JavaScript Solution!
Intuition\n Describe your first thoughts on how to solve this problem. \nThe problem requires us to repeatedly execute a function (fn) at a specified interval (
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\nThe problem requires us to repeatedly execute a function (`fn`) at a specified interval (`t`) and provide a mechanism to stop these executions. The key is to immediately invoke the function once, start the repeated execution using `setInterval`, and return a cancel function that stops the interval when called. This ensures controlled execution and cancellation.\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n1. **Immediate Execution**: Call the function `fn` with the provided arguments (`args`) right away. This satisfies the requirement of an immediate execution.\n\n2. **Repeated Execution**: Use `setInterval` to repeatedly invoke the function every `t` milliseconds, passing the same arguments each time.\n\n3. **Cancellation**: Define a cancel function that clears the interval using `clearInterval`. This function is returned, allowing the caller to stop the repeated executions as needed.\n\n4. **Integration**: Use `setTimeout` outside the function to automatically invoke the cancel function after the specified `cancelTimeMs`, ensuring proper cleanup.\n\n# Complexity\n- **Time complexity**:\n  The time complexity is proportional to the number of executions within the cancel time. Given a total cancel time `cancelTimeMs` and interval `t`, the number of executions is approximately \\( \\text{cancelTimeMs} / t \\). Thus, the time complexity is:\n\n  $$ O(\\text{cancelTimeMs} / t) $$\n\n- **Space complexity**:\n  The function does not use additional data structures or memory that scales with input size. Therefore, the space complexity is:\n\n  $$ O(1) $$\n\n# Code\n```javascript\n/**\n * @param {Function} fn\n * @param {Array} args\n * @param {number} t\n * @return {Function}\n */\nvar cancellable = function(fn, args, t) {\n    // Execute the function immediately\n    fn(...args);\n\n    // Set an interval to repeatedly execute the function\n    let intervalID = setInterval(() => {\n        fn(...args);\n    }, t);\n\n    // Define the cancel function\n    const cancelFn = () => {\n        clearInterval(intervalID);\n    };\n\n    // Return the cancel function\n    return cancelFn;\n};\n\n/**\n * Example usage:\n * \n * const result = [];\n *\n * const fn = (x) => x * 2;\n * const args = [4], t = 35, cancelTimeMs = 190;\n *\n * const start = performance.now();\n *\n * const log = (...argsArr) => {\n *     const diff = Math.floor(performance.now() - start);\n *     result.push({"time": diff, "returned": fn(...argsArr)});\n * }\n * \n * // Create the cancellable function\n * const cancel = cancellable(log, args, t);\n *\n * // Cancel execution after `cancelTimeMs`\n * setTimeout(cancel, cancelTimeMs);\n *\n * // Log results after cancellation\n * setTimeout(() => {\n *     console.log(result); // [\n *                          //     {"time":0,"returned":8},\n *                          //     {"time":35,"returned":8},\n *                          //     {"time":70,"returned":8},\n *                          //     {"time":105,"returned":8},\n *                          //     {"time":140,"returned":8},\n *                          //     {"time":175,"returned":8}\n *                          // ]\n * }, cancelTimeMs + t + 15);\n */\n
['JavaScript']