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You can use .sortBy:

The _.forIn() function returns the iterated object, use _.map() instead:

In terms of performance i think I can write a more performant code using simple for loops as for loops are faster than .map(), .reduce() etc.

You can do the following by traversing the original array once,

Object types in TypeScript are open in the sense that if you have a value of type (say) {a: string, b: number}, while you can be sure that there will be a string property at key "a" and a number property at key "b", you cannot be sure that there will not be properties at keys other than "a" and "b". This openness allows for things like interface and class extensions, where sub-interfaces and sub-classes can have more properties than their parent interfaces and classes without violating the contract of the parent interface or class type. TypeScript does not have "exact types" (as requested in microsoft/TypeScript#12936) where you can say that Exact<{a: string, b: number}> is like {a: string, b: number} but is known to have no other properties but "a" and "b". So unless you add a string index signature to your types, the compiler will balk at the suggestion that the keys of an object will be limited to the ones it knows about. See Why doesn't Object.keys return a keyof type in TypeScript? for a possibly canonical answer here. The safe way to do this is to iterating over a hardcoded array of known keys, like ["numbers", "other_numbers", /* etc */].

But if you already had JavaScript code that was iterating over object properties with something like Object.keys() or Object.entries(), and it was working for you, then you were already running this risk in JavaScript to no apparent harm. If you'd like to continue doing this instead of rewriting your code, then you could always use type assertions to tell the compiler that while you appreciate its concern for the safety of your code, you are sure that it is safe enough for your purposes. For example:

In my limited test below, Lodash handles null & undefined by returning an empty string. It also contradicts the ECMAScript standard by returning -0 for -0 where the native method returns 0. (see: 6.1.6.1.20)

You can check out the source for lodash here for implementation details: https://github.com/lodash/lodash/blob/master/toString.js

The native toString behavior is defined by tc39's ECMAScript 2021 Language Specification 7.1.17

The tests are not exhaustive so feel free to add your own.

I fixed it using the following function, this will only work if the two objects have the same structure.

You could return a large value, for example

Two issues:

• When defining newRmvOverScores and newRmvZeroScores, you actually already execute _.filter, and without a collection argument. They should be functions
• _.flow expects an array of functions, but you don't provide an array, nor are the arguments functions (because of the previous point)

Here is the corrected script:

This is your code with some modifications: