How do Array.find(), findIndex(), some(), and every() work?

• find() — returns the first element where callback returns true, or undefined
• findIndex() — returns the index of first match, or -1
• some() — returns true if at least one element passes (short-circuits)
• every() — returns true only if ALL elements pass (short-circuits)

const users = [
  { id: 1, name: 'Alice', active: true  },
  { id: 2, name: 'Bob',   active: false },
  { id: 3, name: 'Carol', active: true  },
];

users.find(u => u.id === 2);       // { id: 2, name: 'Bob', active: false }
users.findIndex(u => u.id === 2);  // 1
users.find(u => u.id === 99);      // undefined (not found)

users.some(u => u.active);  // true  (stops at Alice)
users.every(u => u.active); // false (stops at Bob)

// Short-circuit saves work
users.some(u => {
  console.log('checking', u.name);
  return u.name === 'Alice'; // only checks Alice — stops immediately
});