slice-ansi 9.x

Complete instructions

Verified against slice-ansi@9.0.0 on 2026-09-08. 6 of 6 examples executed.

slice-ansi

What it does

slice-ansi is an ESM package whose only documented public API is a default-exported function for slicing strings that contain ANSI escape codes. It slices by zero-based visible-column positions rather than raw JavaScript string indexes. Grapheme clusters, including emoji sequences and combining marks, are kept intact.

Version 9 requires Node >=22.

import sliceAnsi from 'slice-ansi';

sliceAnsi(string: string, startSlice: number, endSlice?: number): string;

endSlice is optional. When supplied, it is the zero-based visible-column endpoint. If a complete grapheme cluster would cross that endpoint, that grapheme cluster is excluded.

Import and runtime requirements

The package is ESM. Use a static default import:

import assert from 'node:assert/strict';
import sliceAnsi from 'slice-ansi';

const input = '\u001B[31mred\u001B[39m';
assert.equal(sliceAnsi(input, 0, 3), input);

Run examples with Node 22 or newer. Do not use require() or assume there are named exports. The package export map documents the default function and its types; no other documented public functions are exposed.

ANSI-styled strings

Pass the complete string, including its ANSI escape sequences. Indexes refer to visible columns, not the escape sequences themselves.

import assert from 'node:assert/strict';
import sliceAnsi from 'slice-ansi';

const input = 'plain \u001B[31mred\u001B[39m tail';
const result = sliceAnsi(input, 6, 9);

assert.equal(result, '\u001B[31mred\u001B[39m');

The package can be used directly without chalk or another styling package. Styling libraries are only one possible source of ANSI escape codes.

Grapheme clusters

Do not calculate boundaries with string.length or assume that one JavaScript code unit is one visible character. Emoji sequences and combining-mark sequences are preserved as grapheme clusters.

An emoji sequence can occupy two visible columns. Select its complete visible-column range rather than cutting it at a code-unit boundary:

import assert from 'node:assert/strict';
import sliceAnsi from 'slice-ansi';

const input = 'A👩‍💻B';
assert.equal(sliceAnsi(input, 1, 3), '👩‍💻');

A combining-mark sequence remains intact when selected as one visible column:

import assert from 'node:assert/strict';
import sliceAnsi from 'slice-ansi';

const input = 'e\u0301X';
assert.equal(sliceAnsi(input, 0, 1), 'e\u0301');

When an endpoint would cut across a complete grapheme cluster, that cluster is excluded rather than returned partially:

import assert from 'node:assert/strict';
import sliceAnsi from 'slice-ansi';

const input = 'A👩‍💻B';
assert.equal(sliceAnsi(input, 0, 2), 'A');

Omitting the endpoint

endSlice may be omitted to take the visible suffix beginning at startSlice.

import assert from 'node:assert/strict';
import sliceAnsi from 'slice-ansi';

assert.equal(sliceAnsi('abcdef', 3), 'def');
assert.equal(sliceAnsi('\u001B[32mhello\u001B[39m', 2), '\u001B[32mllo\u001B[39m');

Common mistakes

• Using the older generic-index explanation: v9 documents startSlice and endSlice as visible-column positions. ANSI control sequences do not consume visible columns.
• Splitting graphemes yourself: do not convert the string to code units or assume emoji and combining marks can be sliced independently. v9 keeps grapheme clusters intact.
• Assuming endSlice is inclusive: it is an endpoint; a grapheme cluster that would cross it is excluded.
• Using a CommonJS or named import: v9 is ESM and exposes one documented default export.
• Running on an older Node version: the v9 package metadata requires Node >=22.
• Expecting a CLI or test-runner API: this package exports a function for direct use in a script. describe, it, and expect are not part of its API.

Not covered

This skill does not cover undocumented behavior, invalid argument handling, negative or non-finite indexes, detailed ANSI escape-code edge cases, terminal-width behavior beyond the documented visible-column and grapheme-cluster rules, or package development commands and tests.