Appendix C. Built-in Objects

This appendix lists the built-in constructor functions outlined in the ECMAScript (ES) standard, together with the properties and methods of the objects created by these constructors. ES5-specific APIs are listed separately.


Object() is a constructor that creates objects, for example:

    > var o = new Object(); 

This is the same as using the object literal:

    > var o = {}; // recommended 

You can pass anything to the constructor and it will try to guess what it is and use a more appropriate constructor. For example, passing a string to new Object() will be the same as using the new String() constructor. This is not a recommended practice (it's better to be explicit than let guesses creep in), but still possible:

 > var ...

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