이 문서는 아직 자원 봉사자들이 한국어로 번역하지 않았습니다. 참여해서 번역을 마치도록 도와 주세요!
English (US)의 문서도 읽어보세요.

Message

TypeError: invalid 'instanceof' operand "x" (Firefox) 
TypeError: "x" is not a function (Firefox) 
TypeError: Right-hand side of 'instanceof' is not an object (Chrome) 
TypeError: Right-hand side of 'instanceof' is not callable (Chrome)

Error type

TypeError

What went wrong?

The instanceof operator expects the right hand side operands to be a constructor object, i.e. an object which has a prototype property and is callable.

Examples

"test" instanceof ""; // TypeError: invalid 'instanceof' operand ""
42 instanceof 0;      // TypeError: invalid 'instanceof' operand 0

function Foo() {}
var f = Foo();        // Foo() is called and returns undefined
var x = new Foo();

x instanceof f;       // TypeError: invalid 'instanceof' operand f
x instanceof x;       // TypeError: x is not a function

To fix these errors, you will either need to replace the instanceof operator with the typeof operator, or to make sure you use the function name, instead of the result of its evaluation.

typeof "test" == "string"; // true
typeof 42 == "number"      // true

function Foo() {}
var f = Foo;               // Do not call Foo.
var x = new Foo();

x instanceof f;            // true
x instanceof Foo;          // true

See also

 

문서 태그 및 공헌자

이 페이지의 공헌자: fscholz, nbp
최종 변경자: fscholz,