import/no-cycle Restriction

What it does

Ensures that there is no resolvable path back to this module via its dependencies.

This includes cycles of depth 1 (imported module imports me) to "∞" (or Infinity), if the maxDepth option is not set.

Why is this bad?

Dependency cycles lead to confusing architectures where bugs become hard to find. It is common to import an undefined value that is caused by a cyclic dependency.

Examples

Examples of incorrect code for this rule:

// dep-b.js
import "./dep-a.js";
export function b() {
  /* ... */
}

// dep-a.js
import { b } from "./dep-b.js"; // reported: Dependency cycle detected.
export function a() {
  /* ... */
}

In this example, dep-a.js and dep-b.js import each other, creating a circular dependency, which is problematic.

Examples of correct code for this rule:

// dep-b.js
export function b() {
  /* ... */
}

// dep-a.js
import { b } from "./dep-b.js"; // no circular dependency
export function a() {
  /* ... */
}

In this corrected version, dep-b.js no longer imports dep-a.js, breaking the cycle.

References

• Rule Source