将字符串转换为类型（node.js）

Question

I know this seems like an odd problem, but at the moment I'm creating a webserver to save data to a mongodb database using mongoose. To use that, I need to create a model with a schema which basically defines the values I can search to, as well as the type they should be (String, Number, etc.)

As I said before, since it's a webserver, I'd like to make it so the webserver will create the model and the schema, with a body object in the request. However, there is an issue. I can only pass the type (String, Number, etc.) as a string. I've come up with a solution to parse the value into a type, that being the code below

    getTypeByString: function (string) {
        if (string == 'String') {
            return String
        }
        if (string == 'Number') {
            return Number
        }
        if (string == 'Array') {
            return Array
        }
        if (string == 'Object') {
            return Object
        }
    }

However, I feel like there is probably a more simple solution. If there is or isn't, please let me know, I'd like to release my code on GitHub eventually. and I'd like it to be as dynamic and simple as possible. Thank you in advance

Answer 1

In regards to getting a defined type from a string you can use an object to define the types and use the string as the key.

const DefinedTypes = {
  String: String,
  Number: Number,
  Array: Array,
  Object: Object,
  CustomType: classOfCustomType
};

Using it.

const typeAsString = 'String';
const type = DefinedTypes[typeAsString];

Answer 2

You could use a switch statement to make the code a bit simpler:

getTypeByString: function(stype){
    switch(stype){
        case "String": return String;
        case "Number": return Number;
        case "Array": return Array;
        case "Object" : return Object;
        default: return null; // or throw an error
    };
};

Answer 3

String , Number , Array and Object are also properties of the global variable (or window variable if you are in a browser).

You can check it yourself by evaluating:

global['String'] === String // true

For this reason, you can just use the string to lookup the type within the global object, and return it:

getTypeByString: function (string) {
  if (['String', 'Number', 'Array', 'Object'].includes(string)) // be sure that you are actually returning a type
    return global[string];
  return null;