Element implicitly has an 'any' type because the index expression is not of type 'number' for enum while converting string to enum in typescript

Question

i'm having a typescript shown below.

enum Categories {
    textbox = 1,
    password
}

let typedata:string ="textbox";
let enumdata:Categories;

I want to convert this textbox string to enum. So that I can assign it in enumdata variable. When i tried to do this using

enumdata=Categories[typedata]

i'm getting an error

Element implicitly has an 'any' type because the index expression is not of type 'number'

Please let me know if anyone faced this issue. Please provide me with example if you found a solution for this.

My typescript version is 2.6.2

tsconfig.json

{
  "compilerOptions": {
      "module": "commonjs",
      "target": "es6",
      "lib": [
        "dom",
        "es2015"
      ],
      "noImplicitAny": false,
      "sourceMap": true,
      "rootDir": "src",
      "outDir": "dist",
      "noEmitOnError": true
  }
}

Thank you Vipin

Answer 1

In typescript, enums are only indexable by number and the exact property name.

It expects the identifier textbox or 0 with type of "textbox" or number, but receives that value as type of string.

To work around this you can declare a type that ensures the right property name is used to get the corresponding enum value. eg:

enum Categories {
    textbox = 1,
    password
}

declare type CategoryType = keyof typeof Categories;

const getCategory = (key: CategoryType) => Categories[key];
/* The following will work as well, but does not ensure the correct typecheck when calling the function. 
   However you can keep you 'typedata' field as type of  string. */
// const getCategory = (key: string) => Categories[key as CategoryType];

let enumdata: Categories;
const typedata: CategoryType = "textbox";

enumdata = getCategory(typedata);

...or simply

const typedata: string = "textbox";
enumdata = Categories[typedata as CategoryType];