How to transform a Array to a map in Javascript/Typescript

This might be an easy one but I thought it is worth saving it here.
Let's assume you want to create a HashMap in typescript or javascript with http status codes and corresponding messages. This might be useful within a frontend error handler.
Here is your error-messages.json

[


  {"code": 403,    "message": "You are not permitted to use this action."  },


  {"code": 400,    "message": "The request was incomplete or wrong."  },  


  {"code": 500,    "message": "A general error has occured."  }


]

here is how you could use it in your code:

// Map with error codes


  errorCodeMapping: Map<number, string> = new Map<number, string>();


// read error codes as json map


let array = Array.from(require("./error-messages.json"));


// map array to errorCode Map


this.errorCodeMapping = new Map(array.map((i: ErrorMessage): [number, string] => [i.code, i.message]));


// get a message for an error code


let msg: string = this.errorCodeMapping.get(403);