ts-get

Archived. Use optional chaining instead :)

Alternative to lodash.get that makes it typed and cool as if optional chaining proposal is there.

Means you're not only safely navigate object, but you're also getting 100% autocomplete and type-safeness 🎉

Important comment from the author :)

Please, be aware of how this is working, and take a look limitations below, this is good to get only primitive values not an objects! (at least without generics/castings etc, which makes no sense and you can use lodash then). You better use ts-optchain if browsers your are supporting, have Proxy support. If not, use ts-optchain anyway but with typescript transformer or babel-plugin that you can find in their docs. More than that, optional chaining proposal has moved to Stage 3 recently, meaning it will be in TS very soon (version 3.7.0 to be precise)

This was nice experiment, but performance limitations of try catch and problems with type inference if object is accessed is making this thing dangerous and not as cool as I thought when I wrote it initially and started using it 😇

Usage and examples

import get from 'ts-get'

 type SomeType = {
  optionalField?: string
  nested?: {
    dangerousAccess?: string
  }
 } | undefined | null
 
 const emptyObject: SomeType = {}
 const withOneOptionalField: SomeType = {
    optionalField: "value",
 }
 
 get(emptyObject, it => it.optionalField, "default") // -> "default"
 get(withOneOptionalField, it => it.optionalField, "default") // -> "value"
 get(withOneOptionalField, it => it.nested.dangerousAccess, "default") // -> "default"
 get(withOneOptionalField, it => it.unknownField, "default") // -> Type error, `unknownField` doesn't exist on type
 get(withOneOptionalField, it => it.optionalField, 5) // -> Type error, third argument is not assignable to type `string`

Difference with lodash.get behavior

• If your path gets null at the end, it will bail out to defaultValue or undefined. If you would like to get null returned anyway, just pass it as a defaultValue

Known issues/limitations:

• If your type field is of type null and only null or undefined your field will be of type {}[]. I have no idea how to fix it 🤷‍♂️ PR Welcome 😇🙏

type A = {
  field: null | undefined// -> {}[] inside of the callback and as return type too
}

• If you return not a primitive but an object, all its nested fields will be Required e.g. all undefined and null will be removed.

import get from 'ts-get'
type A = {
  field?: {
    optional?: string | null
  }
}
const input: A = {}
const res = get(input, it => it.field)
res // <== Will be inferred as { optional: string }, without null and ? (undefined) which is wrong, but seems to be impossible to infer.

You can solve this issue passing down generics implicitly

import get from 'ts-get'
type A = {
  field?: {
    optional?: string | null
  }
}
const input: A = {}
const res = get<A, A['field']>(input, it => it.field)
res // <== Will be inferred properly