useHookAtTopLevel

Diagnostic Category: lint/correctness/useHookAtTopLevel

JSX and TSX

Since: v1.0.0 Sources:

Same as: react-hooks/rules-of-hooks

Enforce that all React hooks are being called from the Top Level component functions.

This rule should be used only in React projects.

To understand why this required see https://reactjs.org/docs/hooks-rules.html#only-call-hooks-at-the-top-level

Examples

Invalid

function Component1({ a }) {
    if (a == 1) {
        useEffect();
    }
}

code-block.js:3:9 lint/correctness/useHookAtTopLevel ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ This hook is being called conditionally, but all hooks must be called in the exact same order in every component render.
  
    1 │ function Component1({ a }) {
    2 │     if (a == 1) {
  > 3 │         useEffect();
      │         ^^^^^^^^^
    4 │     }
    5 │ }
  
  ℹ For React to preserve state between calls, hooks needs to be called unconditionally and always in the same order.
  
  ℹ See https://reactjs.org/docs/hooks-rules.html#only-call-hooks-at-the-top-level

function Component1({ a }) {
    if (a != 1) {
        return;
    }

    useEffect();
}

code-block.js:6:5 lint/correctness/useHookAtTopLevel ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ This hook is being called conditionally, but all hooks must be called in the exact same order in every component render.
  
    4 │     }
    5 │ 
  > 6 │     useEffect();
      │     ^^^^^^^^^
    7 │ }
    8 │ 
  
  ℹ Hooks should not be called after an early return.
  
    1 │ function Component1({ a }) {
  > 2 │     if (a != 1) {
      │                  
  > 3 │         return;
      │         ^^^^^^^
    4 │     }
    5 │ 
  
  ℹ For React to preserve state between calls, hooks needs to be called unconditionally and always in the same order.
  
  ℹ See https://reactjs.org/docs/hooks-rules.html#only-call-hooks-at-the-top-level

Valid

function Component1() {
    useEffect();
}

useHookAtTopLevel

Examples

Invalid

Valid

Related links