[mariazuheros]

Summary

compat/toString converts values with String(value), which asks an object for its string representation and never reads valueOf(). lodash coerces with value + '', so the default hint applies and valueOf() is read first. Objects that carry their value in valueOf come out as [object Object]:

toString({ valueOf: () => 7 });
// es-toolkit: '[object Object]'
// lodash:     '7'

escape({ valueOf: () => '<a>' });
// es-toolkit: '[object Object]'
// lodash:     '&lt;a&gt;'

camelCase({ valueOf: () => 'a b' });
// es-toolkit: 'objectObject'
// lodash:     'aB'

Every compat function that renders its input through toString inherits the gap: camelCase, capitalize, deburr, escape, escapeRegExp, kebabCase, lowerCase, lowerFirst, snakeCase, startCase, toLower, toUpper, upperCase, upperFirst, words, pad, padStart, padEnd, split, replace and repeat.

Fix

Coerce with concatenation so the conversion uses the default hint, mirroring lodash's baseToString. Symbols return before that point because they throw when concatenated, which is also why lodash checks for symbols first. Reusing the existing isSymbol predicate keeps wrapped symbols such as Object(Symbol('a')) working.

trim and truncate build their string from the value's own toString() method instead of this helper, so they are not covered by this change.

Tests

Added regression cases for objects with a custom valueOf, for values that must keep their string representation (plain objects, dates and regular expressions), and for wrapped symbols. Verified against lodash 4.17.21. The es-toolkit/compat bundle size snapshots that pull in toString are updated in a separate commit.

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Project	Deployment	Actions	Updated (UTC)
es-toolkit	Ready	Preview	Aug 22, 2026 8:40am