Why Does JavaScript Display '[object Object]' When Alerting an Object?

Understanding the Meaning of "[object Object]"

When trying to alert a returned value from a function, you may encounter the puzzling "[object Object]" message. This issue arises due to the default serialization of an object in JavaScript.

Reasons for "[object Object]"

Typically, "object" refers to the structural nature of a thing. However, in JavaScript, "Object objects" are a specific type with a constructor function named Object (note the capital "O").

This distinction is important because other types of objects exist in JavaScript, such as:

• Function objects: stringify(function()) -> [object Function]
• Array objects: stringify([]) -> [object Array]
• RegExp objects: stringify(/x/) -> [object RegExp]
• Date objects: stringify(new Date) -> [object Date]

Conclusion

When referring to "objects" in JavaScript, it generally means "Object objects," which are distinct from the broader structural concept of "object." Therefore, the "[object Object]" message indicates the serialization of a specific instance of an Object object, rather than a generic object.

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