Hash algorithm works poorly on objects

[rmadsen]

This package seems to have a couple issues. First, the 1.0.3 version uploaded to npm is different than the package here. However, regardless of whether using the hashcode implementation from GitHub or npm, the same bad behavior occurs:

var hc = require('hashcode') // or `require('hashcode').hashCode()` for the npm version
hc.value({"a": "1", "b": "3"}) // Outputs: 944008200
hc.value({"a": "2", "b": "2"}) // Outputs: 944008200
hc.value({"val1": "abc", "val2": "def", "val3": "unchanged"}) // Outputs -330168938
hc.value({"val1": "abb", "val2": "deg", "val3": "unchanged"}) // Outputs -330168938

Take any object with string values, and call its corresponding hashcode hash1. Now duplicate that object and 'increment' one string value and 'decrement' a different string value. Despite it being a completely different object, this implementation will still output hash1.

I think the object method needs to include the result so far in the call to hash(property + value(obj[property])). Even then, hash functions are notoriously difficult to get right, so I don't know if there are other issues with this package.