JavaScript: Run a given array of promises in series

Last update on July 05 2025 13:05:17 (UTC/GMT +8 hours)

JavaScript fundamental (ES6 Syntax): Exercise-150 with Solution

Run Promises in Series

Write a JavaScript program to run a given array of promises in series.

Use Array.prototype.reduce() to create a promise chain, where each promise returns the next promise when resolved.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2

// Define the runPromisesInSeries function
const runPromisesInSeries = ps => ps.reduce((p, next) => p.then(next), Promise.resolve());

// Define a delay function that returns a promise resolving after a specified time
const delay = d => new Promise(r => setTimeout(r, d));

// Executes each promise sequentially, taking a total of 3 seconds to complete
runPromisesInSeries([() => delay(1000), () => delay(2000)]);

Flowchart:

For more Practice: Solve these Related Problems:

Write a JavaScript program that runs an array of promise-returning functions in series, ensuring each promise resolves before starting the next.
Write a JavaScript function that chains promises sequentially using Array.reduce to process asynchronous tasks one after another.
Write a JavaScript program that executes promises in order and collects their results into an array, handling errors gracefully.

Go to:

PREV : Random Element from Array.
NEXT : Run Function in Web Worker.

Improve this sample solution and post your code through Disqus