What is the time and space complexity of Promise Chaining?

Time complexity: O(1). Space complexity: O(1).

Promise Chaining

Easy

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Solution Guide: Promise Chaining

Approach

Chain .then() calls to sequence dependent async operations: first fetch the user, then use the resolved user object to fetch their posts. Each .then() returns a new promise, enabling flat chaining instead of nesting. A single .catch() at the end handles errors from any step.

Complexity Analysis

Time: O(1)
Space: O(1)

Pattern

Promise Chaining

Why It Works

Each .then() callback receives the resolved value of the previous promise and returns a new promise. This creates a sequential pipeline where the output of one async step feeds into the next.

Updated Feb 2026