How to check if an object has an undefined property?
To check if an object does not actually have such a property, and will therefore return undefined by default when you try and access it: To check if the value associated with an identifier is the special value undefined, or if that identifier has not been declared.
What does undefined property in stdClass mean?
Since it says the undefined property is in stdClass, this means that the object in question is not actually the User class that you think it is. This would generally imply that something went wrong with the creation of the object.
Why is the property undefined in PHP stack overflow?
The obvious explanation would be that the property is defined, but is protected. This means that it is only accessable to this and extended classes. However, the error message does suggest some other error. The class is a User class, but the error suggest it is a property of stdClass.
Is the undefined property in JavaScript read only?
In versions of JavaScript prior to ECMAScript 5, the property named “undefined” on the global object was writeable, and therefore a simple check foo === undefined might behave unexpectedly if it had accidentally been redefined. In modern JavaScript, the property is read-only.
What’s the difference between obj.prop and undefined?
We can clearly see that typeof obj.prop == ‘undefined’ and obj.prop === undefined are equivalent, and they do not distinguish those different situations. And ‘prop’ in obj can detect the situation when a property hasn’t been defined at all and doesn’t pay attention to the property value which may be undefined.
Can you check an object and its property at the same time?
You can’t check an object and its property at the same time. For example, this x.a === undefined or this typeof x.a == ‘undefined’ raises ReferenceError: x is not defined if x is not defined. Variable undefined is a global variable (so actually it is window.undefined in browsers).