What exactly is a hash in regards to JSON?

Question

I am learning JSON, but I found out that you can put what are called "hashes" into JSON as well? Where can I find out what a hash is? Or could you explain to me what a hash is? Also, what's a hashmap? I have experience in C++ and C#, and I am learning JS, Jquery, and JSON.

Answer 1

A Hash is a sparse array that uses arbitrary strings/objects (depending on the implementation, this varies across programming languages) rather than plain integers as keys.

In Javascript, any Object is technically a hash (also referred to as a Dictionary, Associative-Array, etc).

Examples:

  var myObj = {}; // Same as = new Object();   myObj['foo'] = 'bar';    var myArr = []; // Same as = new Array();   myArr[0] = 'foo';   myArr[1] = 'bar';   myArr['blah'] = 'baz'; // This will work, but is not recommended. 

Now, since JSON is basically using JS constructs and some strict guidelines to define portable data, the equivalent to myObj above would be:

{ "foo" : "bar" }; 

Hope this helps.