Objects and Associative Arrays

The JavaScript Object is very versatile and useful. It works a little like the Object base type in Java and the associative array type like %hash from Perl, dict from Python or array from PHP, and is the best of both worlds.

You can also use them for String to Object mapping.

You can initialize a JavaScript Object using shorthand syntax like this:

var Obj = new Object();
var Obj = {};

You can interchange item indexing and member selection. Both operations are equivalent.

Obj.a == Obj(‘a’);

The only type you can use for keys is Strings, so if you index an Object on another Object, it converts the index to a string with the toString function.

Obj[1] == Obj[(1).toString()] == Obj['1'];

If you were used to the real hash mappings you might find in Python or Java, you would need to find a JavaScript library to provide that functionality.

There is currently no mechanism to overload item indexing in any JavaScript implementation, and neither is there a default hash algorithm for objects.

You will be able to find this functionality from a sound library that will give you an associative array type with functions similar to getItem, setItem, hasItem and delItem.

The library should also provide a general hash algorithm that returns good default hashes for every built-in type with polymorphic hash member functions.

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