| 1 | --- |
| 2 | title: Early Return from Functions |
| 3 | impact: LOW-MEDIUM |
| 4 | impactDescription: avoids unnecessary computation |
| 5 | tags: javascript, functions, optimization, early-return |
| 6 | --- |
| 7 | |
| 8 | ## Early Return from Functions |
| 9 | |
| 10 | Return early when result is determined to skip unnecessary processing. |
| 11 | |
| 12 | **Incorrect (processes all items even after finding answer):** |
| 13 | |
| 14 | ```typescript |
| 15 | function validateUsers(users: User[]) { |
| 16 | let hasError = false |
| 17 | let errorMessage = '' |
| 18 | |
| 19 | for (const user of users) { |
| 20 | if (!user.email) { |
| 21 | hasError = true |
| 22 | errorMessage = 'Email required' |
| 23 | } |
| 24 | if (!user.name) { |
| 25 | hasError = true |
| 26 | errorMessage = 'Name required' |
| 27 | } |
| 28 | // Continues checking all users even after error found |
| 29 | } |
| 30 | |
| 31 | return hasError ? { valid: false, error: errorMessage } : { valid: true } |
| 32 | } |
| 33 | ``` |
| 34 | |
| 35 | **Correct (returns immediately on first error):** |
| 36 | |
| 37 | ```typescript |
| 38 | function validateUsers(users: User[]) { |
| 39 | for (const user of users) { |
| 40 | if (!user.email) { |
| 41 | return { valid: false, error: 'Email required' } |
| 42 | } |
| 43 | if (!user.name) { |
| 44 | return { valid: false, error: 'Name required' } |
| 45 | } |
| 46 | } |
| 47 | |
| 48 | return { valid: true } |
| 49 | } |
| 50 | ``` |
| 51 |