Array I

Question

What does the code snippet to the right output by console.log?

Snippet

const a = [0]
console.log(a.length)
a[3] = 3
console.log(a.length)
for (let item of a) {
  console.log(item)
}
a.map(item => {console.log(item)})
a.forEach(item => {console.log(item)})
console.log(Object.keys(a))
delete a[3]
console.log(a.length)
a[2] = 2
a.length = 1
console.log(a[0],a[1],a[2])

Source

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