Private members should be marked as
readonly JS-0368
Anti-pattern
Major
6 months ago
—
6 months old
Member 'appId' is never reassigned; mark it as
readonly 1import PersistenceService from './persistenceService'
2
3class LocalStoragePersistenceService implements PersistenceService {
4 private appId: string 5
6 constructor(appId: string) {
7 this.appId = appId
Description
Private members are marked as readonly if they're never modified outside of the constructor.
Bad Practice
class Container {
// These member variables could be marked as readonly
private neverModifiedMember = true;
private onlyModifiedInConstructor: number;
public constructor(
onlyModifiedInConstructor: number,
// Private parameter properties can also be marked as readonly
private neverModifiedParameter: string,
) {
this.onlyModifiedInConstructor = onlyModifiedInConstructor;
}
}
Recommended
class Container {
// Public members might be modified externally
public publicMember: boolean;
// Protected members might be modified by child classes
protected protectedMember: number;
// This is modified later on by the class
private modifiedLater = 'unchanged';
public mutate() {
this.modifiedLater = 'mutated';
}
}