CtrlK
BlogDocsLog inGet started
Tessl Logo

tessl/npm-string-length

Get the real length of a string by correctly counting astral symbols and ignoring ANSI escape codes

—

Pending
Quality

Pending

Does it follow best practices?

Impact

Pending

No eval scenarios have been run

SecuritybySnyk

Pending

The risk profile of this skill

Overview
Eval results
Files

String Length

String Length provides accurate string length calculation by correctly counting Unicode astral symbols (like emojis) as single characters and optionally ignoring ANSI escape codes. Unlike JavaScript's native String#length which erroneously counts astral symbols as multiple characters, this library uses the modern Intl.Segmenter API for precise Unicode grapheme cluster segmentation.

Package Information

  • Package Name: string-length
  • Package Type: npm
  • Language: JavaScript (ES Module)
  • Installation: npm install string-length

Core Imports

import stringLength from "string-length";

For TypeScript:

import stringLength from "string-length";
import type { Options } from "string-length";

Note: This is an ES module only package. For CommonJS environments, use dynamic import:

const { default: stringLength } = await import("string-length");

Basic Usage

import stringLength from "string-length";

// Standard JavaScript string length vs string-length
'🐴'.length;           // 2 (incorrect - counts UTF-16 code units)
stringLength('🐴');    // 1 (correct - counts visual character)

// ANSI escape codes are ignored by default
stringLength('\u001B[1municorn\u001B[22m');  // 7 (ignores ANSI codes)

// Complex Unicode sequences (emoji with skin tone modifiers)
stringLength('👊🏽');  // 1 (correct - single visual character)

Capabilities

String Length Calculation

Calculates the real visual length of a string by properly handling Unicode characters and ANSI escape codes.

/**
 * Get the real length of a string by correctly counting astral symbols and ignoring ANSI escape codes
 * @param string - The input string to measure
 * @param options - Configuration options
 * @returns The visual character count
 */
export default function stringLength(string: string, options?: Options): number;

Usage Examples:

import stringLength from "string-length";

// Unicode astral symbols (emojis, mathematical symbols)
stringLength('🐴');                    // 1
stringLength('𠀔');                    // 1 (CJK ideograph)
stringLength('foo𠁐bar𠀃');           // 8
stringLength('🏴󠁧󠁢󠁥󠁮󠁧󠁿❤️谢👪');      // 4 (complex emoji sequence)

// ANSI escape codes handling
stringLength('\u001B[1mfoo\u001B[22m');              // 3 (ignores ANSI by default)
stringLength('\u001B[1mfoo\u001B[22m', {
  countAnsiEscapeCodes: true
});                                                   // 12 (includes ANSI codes)

// Empty strings
stringLength('');                      // 0
stringLength('\u001B[1m\u001B[22m');   // 0 (only ANSI codes)

// Complex Unicode with modifiers
stringLength('👩‍👧‍👦');              // 1 (family emoji)
stringLength('❤️');                   // 1 (heart with variation selector)

Types

export type Options = {
  /**
   * Whether ANSI escape codes should be counted. They are ignored by default.
   * @default false
   */
  readonly countAnsiEscapeCodes?: boolean;
};

Implementation Details

  • Uses Intl.Segmenter() for Unicode-aware string segmentation
  • Depends on strip-ansi package for ANSI escape code removal
  • Requires Node.js 16+ for Intl.Segmenter support
  • Returns 0 for empty strings (both before and after ANSI stripping)
  • Iterates through string segments using for...of loop to count visual characters

Error Handling

The function handles edge cases gracefully:

  • Empty strings return 0
  • Strings containing only ANSI escape codes return 0 (when countAnsiEscapeCodes is false)
  • Invalid Unicode sequences are handled by the native Intl.Segmenter implementation
Workspace
tessl
Visibility
Public
Created
Last updated
Describes
npmpkg:npm/string-length@6.0.x
Publish Source
CLI
Badge
tessl/npm-string-length badge