Combine Multiple Array Iterations
Multiple .filter() or .map() calls iterate the array multiple times. Combine into one loop.
Incorrect (3 iterations):
const admins = users.filter(u => u.isAdmin)
const testers = users.filter(u => u.isTester)
const inactive = users.filter(u => !u.isActive)Correct (1 iteration):
const admins: User[] = []
const testers: User[] = []
const inactive: User[] = []
for (const user of users) {
if (user.isAdmin) admins.push(user)
if (user.isTester) testers.push(user)
if (!user.isActive) inactive.push(user)
}