fix[truncate]: escape string separator in RegExp

[TalhaHunter101]

Summary

Fixes #2129

When options.separator is a string containing RegExp metacharacters (such as ?, +, *, [, (, ., \), truncate in es-toolkit/compat directly interpolates it into new RegExp without escaping. This causes SyntaxError: Invalid regular expression crashes when the separator contains quantifiers or unclosed brackets, and unintended wildcard behavior for ..

Difference from Lodash

import _ from 'lodash';
import { truncate } from 'es-toolkit/compat';

// Separator with '?'
_.truncate('hello world? how are you doing?', { length: 20, separator: '?' });
// => "hello world..."

truncate('hello world? how are you doing?', { length: 20, separator: '?' });
// => crashes with SyntaxError: Invalid regular expression: /(?<result>.*(?:(?!?).))(?:?)/u: Invalid quantifier

// Separator with '['
truncate('section [1] details and notes', { length: 20, separator: '[' });
// => crashes with SyntaxError: Invalid regular expression: Unterminated character class

With this change, truncate escapes string separators using escapeRegExp, matching Lodash's behavior and preventing regex syntax crashes.

Changes

• Escaped string separator with escapeRegExp before building the truncation RegExp.
• Added regression tests in src/compat/string/truncate.spec.ts covering string separators containing RegExp metacharacters (?, [, (, +, *, ., and \).

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Project	Deployment	Actions	Updated
es-toolkit	Error		Oct 1, 2026 10:55pm UTC