format-util

library1.0.5jsnpmunverified

format-util is a lightweight utility that provides string formatting capabilities for browser environments, closely mirroring the functionality of Node.js's built-in `util.format()`. Its core purpose is to allow developers to use familiar C-style printf-like formatting (e.g., `%s` for strings, `%d` for numbers) within client-side JavaScript. The package is currently at version 1.0.5, with its last update recorded over nine years ago, indicating it is an an abandoned project with no ongoing development or planned release cadence. This lack of maintenance means it does not incorporate modern JavaScript features such as native ES module support or TypeScript definitions. While it once served as a convenient way to port Node.js-style utilities to the browser without heavy dependencies, its age and abandonment position it as a legacy solution for new projects. Developers should be aware of the implications regarding security, compatibility with modern toolchains, and the absence of active support.

serialization

npm install format-util

github ↗package ↗

INSTALL

IMPORT

SIG · FORMAT-UTIL

format-util

serializationjavascriptv1.0.5

Install

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Import

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Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

format

✓ const format = require('format-util');

✗ import { format } from 'format-util';

This package is CommonJS-only (CJS) and does not provide native ES module (ESM) exports. Direct `import` statements will fail without a bundler's CJS interop layer.

format (for browser)

✓ var format = require('format-util');

✗ import format from 'format-util';

Designed for older browser environments with CJS bundling (e.g., Browserify). Modern browser applications would typically use native template literals or a more actively maintained library for string formatting, or rely on a bundler to transpile this CJS module.

Type definitions

✓ // No built-in types; define manually if using TypeScript.

✗ import type { FormatFunction } from 'format-util';

The package does not ship with TypeScript declarations. Users must create a `d.ts` file or use `// @ts-ignore` for TypeScript compatibility.

Demonstrates basic string formatting with different specifiers (%s, %d, %j) and argument handling.

const format = require('format-util'); // Basic string formatting: %s for strings let message1 = format('Hello, %s!', 'World'); console.log(message1); // Expected: "Hello, World!" // Formatting with multiple arguments: %d for numbers let message2 = format('User %d logged in from %s.', 123, '192.168.1.100'); console.log(message2); // Expected: "User 123 logged in from 192.168.1.100." // Handling objects: %j for JSON representation let userInfo = { id: 456, name: 'Alice' }; let message3 = format('User data: %j', userInfo); console.log(message3); // Expected: "User data: {\"id\":456,\"name\":\"Alice\"}" // Combining different types and handling extra arguments let message4 = format('Item: %s, Quantity: %d, Price: $%d. Remaining args: %s', 'Laptop', 2, 1200, 'extra data'); console.log(message4); // Expected: "Item: Laptop, Quantity: 2, Price: $1200. Remaining args: extra data" // Example demonstrating a common type mismatch (util.format converts non-numbers to NaN for %d) let message5 = format('The number is %d.', 'forty-two'); console.log(message5); // Expected: "The number is NaN." // This utility is often used for building log messages or dynamic display strings.

Debug

Known issues

breakingThe `format-util` package is abandoned and no longer actively maintained. This means there will be no new features, bug fixes, or security updates. Relying on it in new projects is strongly discouraged.

fix

Migrate to actively maintained alternatives such as native template literals, or if in Node.js, `util.format` directly. For browser environments requiring similar functionality, consider libraries like `sprintf-js` or roll your own simple formatting utility.

affects: >=1.0.5

gotchaThis package is CommonJS-only. Using it directly with ES module `import` syntax will cause runtime errors in native ESM environments (e.g., Node.js with `type: module` or modern browsers) unless a bundler provides CJS-ESM interop.

fix

Use `const format = require('format-util');` in CJS environments. In ESM, either configure your bundler (like Webpack or Rollup) for CJS interop, or use dynamic import `import('format-util').then(module => module.exports);` (though this might not work as expected for simple exports).

affects: >=1.0.0

gotchaThere are no official TypeScript type definitions (`.d.ts` files) available for `format-util`. TypeScript projects will not recognize the `format` function without custom declarations.

fix

Create a declaration file (e.g., `src/types/format-util.d.ts`) with `declare module 'format-util' { function format(...args: any[]): string; export = format; }` or use `// @ts-ignore` to suppress type errors.

affects: >=1.0.0

gotchaThe functionality of `format-util` is a simplified port of Node.js's `util.format`. It may not include all advanced specifiers or behaviors found in the latest Node.js versions of `util.format` (e.g., `%o`, `%O`, custom formatters).

fix

Consult the `format-util` source or Node.js `util.format` documentation for specific behavior. For full Node.js `util.format` compatibility in non-Node environments, consider more comprehensive polyfills or reimplementations.

affects: >=1.0.0

Errors

Common errors & fixes

SyntaxError: Named export 'format' not found. The requested module 'format-util' does not provide an export named 'format'

Attempting to use ES module named import syntax (`import { format } from 'format-util';`) on a CommonJS-only package.

fix

Change the import statement to `const format = require('format-util');` for CommonJS compatibility.

TypeError: format is not a function

Occurs when a bundler's CJS-ESM interop is misconfigured, or when attempting to use a default ESM import (`import format from 'format-util';`) where the CJS module exports a single function via `module.exports = fn;` and the interop doesn't correctly resolve it.

fix

Ensure your bundler correctly handles CommonJS modules. In a Node.js CJS environment, stick to `const format = require('format-util');`.

Cannot find name 'format'.

This error appears in TypeScript projects because the `format-util` package lacks official type definitions.

fix

Add a custom declaration file (e.g., `format-util.d.ts`) containing `declare module 'format-util' { function format(...args: any[]): string; export = format; }` to your project's `src/types` directory or similar.

Upgrade

Version history

1.0.5latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

2 hits · last 30 days

node

Resources

githubhttps://github.com/tmpfs/format-util ↗

packagehttps://www.npmjs.com/package/format-util ↗