Function Signature
function maybeEnvStrings(key: string): string[] | undefined
Parameters
The name of the environment variable to read
Returns
string[] | undefined - An array of trimmed non-empty strings, or undefined if the variable is not set or empty.
Behavior
Returns undefined when:
- The environment variable is not set
- The environment variable is an empty string
- The environment variable contains only whitespace
The function:
- Splits the value on commas
- Trims whitespace from each item
- Filters out empty strings
- Returns an array of the remaining values
Example
import { maybeEnvStrings } from "@load-env/core"
// Optional CORS allowed origins
export const ALLOWED_ORIGINS = maybeEnvStrings("ALLOWED_ORIGINS")
if (ALLOWED_ORIGINS) {
console.log(`CORS enabled for: ${ALLOWED_ORIGINS.join(", ")}`)
app.use(cors({ origin: ALLOWED_ORIGINS }))
} else {
console.log("CORS not configured")
}
// Optional feature flags
export const FEATURE_FLAGS = maybeEnvStrings("FEATURE_FLAGS")
function isFeatureEnabled(feature: string): boolean {
return FEATURE_FLAGS?.includes(feature) ?? false
}
// With default value
export const ADMIN_EMAILS = maybeEnvStrings("ADMIN_EMAILS") ?? []
# Comma-separated values
ALLOWED_ORIGINS=https://example.com,https://app.example.com,https://api.example.com
# Spaces are trimmed
FEATURE_FLAGS=feature1, feature2, feature3
# Empty items are filtered out
TAGS=tag1,,tag2,,,tag3
# Results in: ["tag1", "tag2", "tag3"]
When to Use
Use maybeEnvStrings instead of envStrings when:
- The environment variable is optional
- You want to handle missing values gracefully with
undefined
- You can provide a default array or work without the list
Use envStrings when:
- The environment variable is required for your application
- You want the application to fail fast if the variable is missing
