TypeError [ERR_IMPORT_ASSERTION_TYPE_MISSING] Module Fix

How to fix TypeError [ERR_IMPORT_ASSERTION_TYPE_MISSING]: Module…

Example import

import countryTable from './data/countries.json';

Fix import by

import countryTable from "./data/countries.json" assert { type: "json" };

Proposed by https://github.com/tc39/proposal-import-assertions

Answer source: https://stackoverflow.com/a/70106896

More example importing JSON in ESM

// An import assertion in a static import
import info from `./package.json` assert { type: `json` };

// An import assertion in a dynamic import
const { default: info } = await import("./package.json", {
  assert: {
    type: "json",
  },
});

Difference between import assertion in a static import and a dynamic import

Static import just importing JSON as ANY TYPE.

Dynamic import is importing JSON with the JSON structure type.

More example importing JSON is ES Modules

Read and parse JSON files

import { readFile } from 'fs/promises';
const json = JSON.parse(
  await readFile(
    new URL('./some-file.json', import.meta.url)
  )
);

Leverage the CommonJS require function to load JSON files

import { createRequire } from "module";
const require = createRequire(import.meta.url);
const data = require("./data.json");

Dynamic import and assign to interfaces

interface Thesaurus {
  [key: string]: string[];
}
const { default: thesaurus }: { default: Thesaurus } = await import('./thesaurus-en.json', {
  assert: {
    type: 'json'
  }
});