How to convert an array to a hash map in JavaScript?

How to convert an array to a hash map in JavaScript?

The following is a small snippet in JavaScript to convert an array of objects to a hash map, indexed by the attribute value of object. You can provide a function to evaluate the key of hash map dynamically (run time). Hope this helps someone in future. You can find the gist here: Converts Array of Objects to HashMap.

Is the hash key an object in JavaScript?

There are objects and arrays in JavaScript. Hash you are talking about is an object. If you have a look at the line with var tmp_arr = [], it shows that tmp_arr variable is an array ( []) but not an object ( {} ). So both methods return arrays.

How to get unique values from object array JavaScript?

Such a function could be an hash function that you should write to create a unique key to identify your objects and compare each other. The proper hash function should return the same value if called with objects that have the same composed key.

When does the hash function return the same value?

The proper hash function should return the same value if called with objects that have the same composed key. In your case, when 2 objects have name, date and amount with the same value, the hash function is supposed to return the same value.

How to create hash from string in JavaScript?

How to create hash from string in JavaScript ? In order to create a unique hash from a specific string, it can be implemented using their own string to hash converting function. It will return the hash equivalent of a string. Also, a library named Crypto can be used to generate various types of hashes like SHA1, MD5, SHA256 and many more.

How to reliably hash JSON objects in JavaScript?

The best way to sign and hash JSON objects now is to use JSON Web Tokens. This allows for an object to be signed, hashed and then verified by others based on the signature.

How to turn a string into a hash object in Ruby?

It has all the properties how a valid Hash is typed in Ruby. The string created by calling Hash#inspect can be turned back into a hash by calling eval on it. However, this requires the same to be true of all of the objects in the hash.

How to convert an array to an object in Lodash?

8 Answers 8. Another way with lodash 4.17.2. You should be using _.keyBy to easily convert an array to an object. If required, you can manipulate the array before using _.keyBy or the object after using _.keyBy to get the exact desired result. (Thanks to Ben Steward, good thinking…)

Can you use Lodash’s map function in underscore?

You can use _.map function (of both lodash and underscore) with object as well, it will internally handle that case, iterate over each value and key with your iteratee, and finally return an array. Infact, you can use it without any iteratee (just _.map (obj)) if you just want a array of values.

Which is the best way to use Lodash in JavaScript?

There are other lodash solutions like _.values (more readable for specific perpose), or getting pairs and then map and so on. but in the case your code need flexibility that you can update it in future as you need to preserve keys or transforming values a bit, then the best solution is to use a single _.map as addresed in this answer.