evanw/esbuild · error · Error

Expected value for ${what}${key !== void 0 ? ' ' + quote(key

Error message

Expected value for ${what}${key !== void 0 ? ' ' + quote(key) : ''} to be a string, got ${typeof value} instead

What it means

Error "Expected value for ${what}${key !== void 0 ? ' ' + quote(key) : ''} to be a string, got ${typeof value} instead" thrown in evanw/esbuild.

Source

Thrown at lib/shared/common.ts:140

  return validated
}

type CommonOptions = types.BuildOptions | types.TransformOptions

function pushLogFlags(flags: string[], options: CommonOptions, keys: OptionKeys, isTTY: boolean, logLevelDefault: types.LogLevel): void {
  let color = getFlag(options, keys, 'color', mustBeBoolean)
  let logLevel = getFlag(options, keys, 'logLevel', mustBeString)
  let logLimit = getFlag(options, keys, 'logLimit', mustBeInteger)

  if (color !== void 0) flags.push(`--color=${color}`)
  else if (isTTY) flags.push(`--color=true`); // This is needed to fix "execFileSync" which buffers stderr
  flags.push(`--log-level=${logLevel || logLevelDefault}`)
  flags.push(`--log-limit=${logLimit || 0}`)
}

function validateStringValue(value: unknown, what: string, key?: string): string {
  if (typeof value !== 'string') {
    throw new Error(`Expected value for ${what}${key !== void 0 ? ' ' + quote(key) : ''} to be a string, got ${typeof value} instead`)
  }
  return value
}

function pushCommonFlags(flags: string[], options: CommonOptions, keys: OptionKeys): void {
  let legalComments = getFlag(options, keys, 'legalComments', mustBeString)
  let sourceRoot = getFlag(options, keys, 'sourceRoot', mustBeString)
  let sourcesContent = getFlag(options, keys, 'sourcesContent', mustBeBoolean)
  let target = getFlag(options, keys, 'target', mustBeStringOrArrayOfStrings)
  let format = getFlag(options, keys, 'format', mustBeString)
  let globalName = getFlag(options, keys, 'globalName', mustBeString)
  let mangleProps = getFlag(options, keys, 'mangleProps', mustBeRegExp)
  let reserveProps = getFlag(options, keys, 'reserveProps', mustBeRegExp)
  let mangleQuoted = getFlag(options, keys, 'mangleQuoted', mustBeBoolean)
  let minify = getFlag(options, keys, 'minify', mustBeBoolean)
  let minifySyntax = getFlag(options, keys, 'minifySyntax', mustBeBoolean)
  let minifyWhitespace = getFlag(options, keys, 'minifyWhitespace', mustBeBoolean)
  let minifyIdentifiers = getFlag(options, keys, 'minifyIdentifiers', mustBeBoolean)

View on GitHub (pinned to 6ff1d8b0d8)

Solutions

1. Pass a string value instead of the reported type for this option
2. Convert the value to a string (e.g. with String(value)) before passing it

Example fix

// entryPoints must be strings, not numbers or objects
esbuild.buildSync({ entryPoints: ['src/index.ts'] });

When it happens

Trigger: Thrown at lib/shared/common.ts:140 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of evanw/esbuild@6ff1d8b0d8 (2026-08-03). Data as JSON: /data/errors/9143ed2431a97ded.json. Report an issue: GitHub.