planttheidea / hash-it Goto Github PK

Hi when am I supposed to use it ? From the example code, I assume that objects that have same set of key/ value will produce same hash, so it's quite of verification stuff ?

We're using hash-it to compute cache keys and ran into situations where objects to be hashed look like this

1. { a: 1, b: undefined }
2. { a: 1 }

We can pass it through JSON.stringify() beforehand locally but it would be better if this utility would handle that

So is there any way to exclude object keys where their value is undefined?

The encoding used by hash-it a) makes it trivial to generate collisions (cf.), b) doesn't handle nested dates, and c) doesn't distinguish between different circular references:

import hash from 'hash-it'
    
hash.is(42, "number|42")   // true 
hash.is(null, "null|null") // true 

hash.is(new Date(1970, 0, 1), "Date|0")                                       // true
hash.is(new Date(1970, 0, 1), "1970-01-01T00:00:00.000Z")                     // false
hash.is({ date: new Date(1970, 0, 1) }, { date: "1970-01-01T00:00:00.000Z" }) // true

obj = {}
obj.self = obj
    
hash.is(obj, { "self": "~" }) // true 

arr1 = [obj, obj, obj]
arr2 = [obj, obj]
arr2.push(arr2) 

hash.is(arr1, '[{"self":"~"},"~","~"]') // true
hash.is(arr1, arr2)                     // true

These can be worked around with a more consistent/robust encoding, e.g. nested dates can be detected via this[key] instanceof Date, and strings can be distinguished from other primitives by (always) using a prefix, e.g. "string|Hello, world!".

I haven't used it, but it looks like (your :-) fast-stringify provides a path parameter which can be used to distinguish between the different circular references.