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Find path in given object

Kurapati Mahesh on July 15, 2022

// Problem: /* - Write method findPath - Should take two params: - object - keys separated by dots as string - Return value if it exists ...
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Alex Lohr •

Recursion makes for a simpler solution:

const findPath = (obj, path) => {
  const [item, nextPath] = /([^\.]+)\.(.*)/.exec(path)?.slice(1, 3) || [path];
  return nextPath ? findPath(obj?.[item], nextPath) : obj?.[item];
}
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calinzbaenen profile image
Calin Baenen •

As Frank Wisniewski suggests, try Optional Chaning.
It works on more than just object properties as well. It also lets you optionally call functions.

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urstrulyvishwak profile image
Kurapati Mahesh •

Yes. Optional chaining is latest feature and might not be used (or enabled) everywhere. If someone is using then cool otherwise we need to follow traditional way.

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Jon Randy 🎖️ •

This confused me initially because of the function name - I thought we were going to find a path to a property with a given value, but we're actually doing the opposite. A better name might be getPropertyWithPath

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urstrulyvishwak profile image
Kurapati Mahesh •

findPath similar to getPropertyPath. I hope people would get it as I am referring to object.

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frankwisniewski profile image
Frank Wisniewski •

Does that really make sense?

console.log(
  obj.a?.b?.c?.d
)
// or
console.log(
  obj.a?.b
)
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gives the same result

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calinzbaenen profile image
Calin Baenen •

True, but I þink ðis is more for backwards compatibility.
But yes, newer code should probably use Optional Chaining.

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urstrulyvishwak profile image
Kurapati Mahesh •

Yes. Optional Chaining is the best and more readable.

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Jon Randy 🎖️ •

But this isn't really doing the same thing? It's not dynamic

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frankwisniewski profile image
Frank Wisniewski •

I don't understand what you mean by that..

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urstrulyvishwak profile image
Kurapati Mahesh •

This could be an impossible case as no one could assign key as dot. Anyhow, my solution is to cover the use cases mentioned.

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calinzbaenen profile image
Calin Baenen • • Edited

I think you forgot you can format objects like JSON (JavaScript Object Notation):

let my_obj = {
    "foo": "bar",
    ".":   "baz"
}
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urstrulyvishwak profile image
Kurapati Mahesh •

I was referring to real world scenario. No one uses any object key as dot alone.

Usually, programmers give readable key name based on their requirement.

Everything has its corner cases, I am generalizing concept to find the path. It is not that I need to cover all worst cases.

Hope you guys get it. Also, it would be better if you guys provide solution for the case you are mentioning. That might worth for the people came across this article.

Thank you.

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FJones •

The simplest solution would be to do away with split and instead consider a token-based approach:

"." refers to a field called "." on the root, whereas "foo.." refers to a field called "." on the nested object at root-key "foo". And then "foo...bar" refers to a foo->.->bar path.

However, this also causes some ambiguity: foo.....bar could be either foo->.->.->bar or foo->...->bar.

A generalized solution would then use escape sequences. e.g. \. for a dot literal, \\ for a backslash literal, but that naturally makes parsing the path ever so more complex.

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calinzbaenen profile image
Calin Baenen •

I like ðis approach.
Sure it requires some more complexity and probably takes longer (but not too much) than .split(char_seq) but it gets ðe job done and better.

However, this also causes some ambiguity: foo.....bar could be either foo->.->.->bar or foo->...->bar.

Ðis could be solved by checking ðe more specific case (foo->.->.->ba) first and if ðat fails try ðe simpler one(s).
Of course it won't be perfect but it can at least try to figure out intentions.

 
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Jon Randy 🎖️ •

A Symbol is a valid key 😂

 
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Calin Baenen •

You can also directly define "." in the object declaration as well.

 
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Calin Baenen •

Ðat's why ðey have a .toString() meþod, I believe.

 
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Jon Randy 🎖️ •

Symbols in template strings = TypeError: can't convert symbol to string :)