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- # sigmund
- Quick and dirty signatures for Objects.
- This is like a much faster `deepEquals` comparison, which returns a
- string key suitable for caches and the like.
- ## Usage
- ```javascript
- function doSomething (someObj) {
- var key = sigmund(someObj, maxDepth) // max depth defaults to 10
- var cached = cache.get(key)
- if (cached) return cached
- var result = expensiveCalculation(someObj)
- cache.set(key, result)
- return result
- }
- ```
- The resulting key will be as unique and reproducible as calling
- `JSON.stringify` or `util.inspect` on the object, but is much faster.
- In order to achieve this speed, some differences are glossed over.
- For example, the object `{0:'foo'}` will be treated identically to the
- array `['foo']`.
- Also, just as there is no way to summon the soul from the scribblings
- of a cocaine-addled psychoanalyst, there is no way to revive the object
- from the signature string that sigmund gives you. In fact, it's
- barely even readable.
- As with `util.inspect` and `JSON.stringify`, larger objects will
- produce larger signature strings.
- Because sigmund is a bit less strict than the more thorough
- alternatives, the strings will be shorter, and also there is a
- slightly higher chance for collisions. For example, these objects
- have the same signature:
- var obj1 = {a:'b',c:/def/,g:['h','i',{j:'',k:'l'}]}
- var obj2 = {a:'b',c:'/def/',g:['h','i','{jkl']}
- Like a good Freudian, sigmund is most effective when you already have
- some understanding of what you're looking for. It can help you help
- yourself, but you must be willing to do some work as well.
- Cycles are handled, and cyclical objects are silently omitted (though
- the key is included in the signature output.)
- The second argument is the maximum depth, which defaults to 10,
- because that is the maximum object traversal depth covered by most
- insurance carriers.
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