no-import-assign.md

Pattern: Assignment to imported binding

Issue: -

Description

ES Modules create read-only bindings. Attempting to reassign imported values, modify imported objects, or extend imported namespaces will cause runtime errors. Use local variables instead if you need to modify imported values.

Examples

Example of incorrect code:

import mod, { named } from "./mod.mjs";
import * as ns from "./mod.mjs";

mod = 1;
named = 2;
ns.prop = 3;
ns = {};

Object.assign(ns, { foo: "bar" });

Example of correct code:

import mod, { named } from "./mod.mjs";
import * as ns from "./mod.mjs";

const localMod = mod;
let localNamed = named;
const localNs = { ...ns };

localMod = 1;
localNamed = 2;
localNs.prop = 3;