Не рабоатет import в js

 import { Grid } from "./grid"


const gameBoard = document.getElementById("game-board");

const grid = new Grid(gameBoard)
alert(1)

grid.js: 

 
import { Cell } from "./cell"

const GRID_SIZE = 4;
const CELLS_COUNT = GRID_SIZE * GRID_SIZE

export class Grid {
    constructor(gridElement) {
        this.cells = [];
        for (let i = 0; i < CELLS_COUNT; i++) {
            this.cells.push(
                new Cell(gridElement, i % GRID_SIZE, Math.floor(i / GRID_SIZE))
            );
            
        }
    }
}
cell.js: 

 export class Cell {
    constructor (gridElement, x, y) {
        const cell = document.createElement("div");
        cell.classList.add("cell");
        gridElement.append(cell);
        this.x = x;
        this.y = y;
    }
}