instanceof

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨July 2015⁩. Learn more See full compatibility Report feedback The instanceof operator tests to see if the prototype property of a constructor appears anywhere in the prototype chain of an object. The return value is a boolean value. Its behavior can be customized with Sym

[mooz]

XPCOM においては obj instanceof xpcominterFace とすると，obj.QueryInterface(xpcomInterface) が呼ばれ，その呼び出しが成功すれば true が返される．