What do Object.keys/Object.values/Object.entries do with an array?

const arr = ['a', 'b', 'c'];
 
Object.keys(arr);     // ['0', '1', '2'] — indices
Object.values(arr);   // ['a', 'b', 'c'] — values
Object.entries(arr);  // [['0','a'], ['1','b'], ['2','c']] — pairs

const fruits = ['apple', 'banana', 'orange'];
 
console.log(Object.keys(fruits)); 
// ['0', '1', '2'] — indices as strings!
 
// Missing elements are not counted
const sparse = ['a', , 'c']; // "sparse" array
console.log(Object.keys(sparse)); 
// ['0', '2'] — only existing indices

const fruits = ['apple', 'banana', 'orange'];
 
console.log(Object.values(fruits)); 
// ['apple', 'banana', 'orange'] — like arr.slice()
 
// Missing elements also not counted
const sparse = ['a', , 'c'];
console.log(Object.values(sparse)); 
// ['a', 'c'] — only existing values

const fruits = ['apple', 'banana', 'orange'];
 
console.log(Object.entries(fruits)); 
// [['0', 'apple'], ['1', 'banana'], ['2', 'orange']]
 
// Useful for iteration with indices
Object.entries(fruits).forEach(([index, value]) => {
  console.log(`${index}: ${value}`);
});
// 0: apple
// 1: banana
// 2: orange

// ✅ When you need indices as array
const arr = ['a', 'b', 'c'];
const indices = Object.keys(arr); // ['0', '1', '2']
 
// Better than making loop to get indices

// ✅ Keep only even indices
const arr = ['a', 'b', 'c', 'd'];
const evenIndexed = Object.entries(arr)
  .filter(([index]) => index % 2 === 0)
  .map(([, value]) => value);
  
console.log(evenIndexed); // ['a', 'c']

const arr = ['a', 'b', 'c'];
const keys = Object.keys(arr);
 
// ❌ Mistake — these are strings!
console.log(keys[0] + 1); // '01', not 1!
 
// ✅ Correct — convert to number
console.log(+keys[0] + 1); // 1

const arr = ['a', 'b', 'c'];
 
// ❌ Not the same!
Object.values(arr); // ['a', 'b', 'c']
arr.slice();        // ['a', 'b', 'c'] — same, but clearer
 
// Object.values is more useful with objects