Convert string (url style) to navigate in Object

Question

Current string: folder1/folder2/folder3

I need to convert in: ['folder1']['folder2']['folder3']

What I tried:

let folder = "folder1/folder2/folder3";

let splittedFolder = folder.split('/');
let newFolder = splittedFolder.join('[' ']');

I think I am absolutely wrong.... I want to achieve somethink like userDB['folder1']['folder2']['folder3'] to navigate into an Object and edit it.

Are you trying to create an array? Or a string containing []? — DeborahK
– DeborahK, Commented Feb 23, 2019 at 19:11

CertainPerformance · Accepted Answer · 2019-02-23 19:17:55Z

1

You might split by slashes, then map to enclose each string with ['']s, then join again:

let folder = "folder1/folder2/folder3";
const output = folder
  .split('/')
  .map(str => `['${str}']`)
  .join('');
console.log(output);

But you can't navigate a normal object with a string like this unless you use eval, which you really shouldn't use. If the literal code

userDB['folder1']['folder2']['folder3']

would result in accessing the desired nested value, then to get to it from your input, use reduce instead:

const val = folder.split('/')
  .reduce((a, key) => a[key], userDB);

Or, to handle possible undefined objects in between:

const val = folder.split('/')
  .reduce((a, key) => a !== undefined ? a[key] : undefined, userDB);

edited Feb 23, 2019 at 19:17

answered Feb 23, 2019 at 19:10

CertainPerformance

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4 Comments

Vueer Over a year ago

Thank you, it works! :) But how do I can remove the first? because will be an empty one: ['']

CertainPerformance Over a year ago

Do you mean that your real input string has a leading slash? If so, slice it off first. folder.slice(1).split(...

Vueer Over a year ago

Thanks so much :) Your example from above works well. I get the value from the object. But what if I want to change this value? val = newValue; not works because the variable val "is never used", also if I change to let val...

CertainPerformance Over a year ago

Pop off the last substring from the array first, then use the same reduce method as above to get lastObj (while iterating over all but the last item in the array), then do lastObj[lastProp] = newVal

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