# ``typeof`` operator is allowed only in expression contexts Rule ``arkts-no-type-query`` **Severity: error** ArkTS supports ``typeof`` operator only in the expression context. Using ``typeof`` to specify type notations is not supported. ## TypeScript ``` let n1 = 42 let s1 = "foo" console.log(typeof n1) // "number" console.log(typeof s1) // "string" let n2: typeof n1 let s2: typeof s1 ``` ## ArkTS ``` let n1 = 42 let s1 = "foo" console.log(typeof n1) // "number" console.log(typeof s1) // "string" let n2: number let s2: string ``` ## See also - Recipe 001: Objects with property names that are not identifiers are not supported (``arkts-identifiers-as-prop-names``) - Recipe 002: ``Symbol()`` API is not supported (``arkts-no-symbol``) - Recipe 029: Indexed access is not supported for fields (``arkts-no-props-by-index``) - Recipe 059: ``delete`` operator is not supported (``arkts-no-delete``) - Recipe 066: ``in`` operator is not supported (``arkts-no-in``) - Recipe 144: Usage of standard library is restricted (``arkts-limited-stdlib``)