2821. Delay the Resolution of Each Promise

Description

Given an array functions and a number ms, return a new array of functions.

• functions is an array of functions that return promises.
• ms represents the delay duration in milliseconds. It determines the amount of time to wait before resolving each promise in the new array.

Each function in the new array should return a promise that resolves after a delay of ms milliseconds, preserving the order of the original functions array. The delayAll function should ensure that each promise from functions is executed with a delay, forming the new array of functions returning delayed promises.

Example 1:

Input: 
functions = [
   () => new Promise((resolve) => setTimeout(resolve, 30))
], 
ms = 50
Output: [80]
Explanation: The promise from the array would have resolved after 30 ms, but it was delayed by 50 ms, thus 30 ms + 50 ms = 80 ms.

Example 2:

Input: 
functions = [
    () => new Promise((resolve) => setTimeout(resolve, 50)),
    () => new Promise((resolve) => setTimeout(resolve, 80))
], 
ms = 70
Output: [120,150]
Explanation: The promises from the array would have resolved after 50 ms and 80 ms, but they were delayed by 70 ms, thus 50 ms + 70 ms = 120 ms and 80 ms + 70 ms = 150 ms.

Constraints:

• functions is an array of functions that return promises
• 10 <= ms <= 500
• 1 <= functions.length <= 10

Solutions

Solution 1

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function delayAll(functions: Function[], ms: number): Function[] {
    return functions.map(fn => {
        return async function () {
            await new Promise(resolve => setTimeout(resolve, ms));
            return fn();
        };
    });
}