ESLint Plugin UseMemo Recommendations

Detect potentially heavy operations in React components and recommend using useMemo.

Rule Details

This rule looks for certain patterns in React component code that might indicate computationally heavy operations, such as:

• Nested loops
• Recursive function calls
• Chains of array operations like mapping, filtering, and sorting on potentially large arrays
• Potentially expensive mathematical calculations (e.g., exponentiation, trigonometric functions, logarithms)

When the rule detects one of these patterns, it suggests wrapping the code in useMemo to potentially improve performance.

Examples of incorrect code for this rule:

const Component = () => {
  const array = [
    /* large array */
  ]
  const mapped = array.map(/* ... */).filter(/* ... */).sort(/* ... */)

  return <div>{mapped}</div>
}

const Component = () => {
  const factorial = n => {
    if (n <= 1) return 1
    return n * factorial(n - 1)
  }

  return <div>{factorial(10)}</div>
}

Examples of correct code for this rule:

const Component = () => {
  const array = [
    /* large array */
  ]
  const mapped = useMemo(
    () => array.map(/* ... */).filter(/* ... */).sort(/* ... */),
    []
  )

  return <div>{mapped}</div>
}

const Component = () => {
  const result = useMemo(() => {
    const factorial = n => {
      if (n <= 1) return 1
      return n * factorial(n - 1)
    }
    return factorial(10)
  }, [])

  return <div>{result}</div>
}

Installation

1. Install eslint

npm install --save-dev eslint

2. Install plugin

npm install --save-dev eslint-plugin-usememo-recommendations

3. Add plugin to your config

{
  "plugins": ["usememo-recommendations"],
  "rules": {
    "usememo-recommendations/detect-heavy-operations": "warn"
  }
}