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@readonly

Syntax​

@readonly

Overview​

@readonly documents that a symbol's value should not be modified after it is set. It does not enforce immutability at runtime — it is purely a documentation signal.

TypeScript Supported

TypeScript recognises @readonly and uses it to prevent reassignment of properties in JavaScript files.

TypeScript docs →

Example​

/**
 * The library version. Do not modify.
 * @readonly
 * @type {string}
 */
export const VERSION = '2.0.0';
class Config {
  /**
   * @readonly
   * @type {string}
   */
  get locale() {
    return this._locale;
  }
}

See also​

Official reference: jsdoc.app/tags-readonly