Coding
AI Prompt for Utility Functions
Build a clean utility library with this AI prompt: consistent helper functions with docs, examples and tests — pure, dependency-free, ready to drop in.
The prompt
Role: You are a [LANGUAGE] developer who crafts small, perfect utility functions — the kind that end up copied into every project. Context: I need helper utilities for [DOMAIN, e.g. date formatting, string manipulation]. Functions needed: [FUNCTION_LIST]. Style: [STYLE: pure functions, no external dependencies, typed]. Task: 1) Write each utility as a small, pure, well-named function with docs/comments. 2) Keep signatures consistent across all utilities (parameter order, option objects, return conventions). 3) Handle edge cases (null inputs, empty strings, invalid dates) gracefully in each. 4) Provide one usage example per function. 5) Suggest the file/module organization. Format: One section per function (code + example), then the organization suggestion. Request a consistency audit across the set: uniform parameter order, option-object conventions, and error behavior. A utility library feels professional when every function guesses the same way, and the AI can enforce that uniformity. Constraints: Zero dependencies. Pure functions only — no hidden side effects or global state. Each function does exactly one thing.
Variables to fill in
Replace each [variable] in the prompt with your own details:
[LANGUAGE] [DOMAIN] [FUNCTION_LIST] [STYLE]
Example input
LANGUAGE=TypeScript, DOMAIN=date and string formatting helpers, FUNCTIONS=formatDate, truncate, slugify, capitalize, deepClone, STYLE=pure functions, no dependencies
How to use this prompt
List all the helpers you want in one go — the AI keeps naming and style consistent across the batch. Insist on pure functions; utilities with hidden side effects cause bugs.
Tips for the best results
- Ask for the test cases too — utilities are the easiest code to test and the most reused.
- Request a 'no dependencies' constraint to keep the utils portable between projects.
- Have it check edge cases like empty string, null, and unicode for every string helper.
Frequently asked questions
Can it generate a whole utility library at once?
Yes — list them all in FUNCTIONS and ask for consistent naming, signatures, and JSDoc across the set.
How many helpers should I generate at once?
Five to ten per batch keeps naming and style consistent. Larger batches drift; generate in groups and ask for the consistency audit each time.