What does this log?

const m = "Due: 2026-10-02".match(/(\d{4})-(\d{2})-(\d{2})/);
console.log(m[0], m[2], m.length);

1. 2026-10-02 10 4
2. 2026 10 3
3. 2026-10-02 02 4
4. 2026-10-02 10 3

What does this log?

console.log("Lovelace, Ada".replace(/(?<last>\w+), (?<first>\w+)/, "$<first> $<last>"), "2026-10-02".replace(/(\d{4})-(\d{2})-(\d{2})/, "$2/$3/$1"));

1. Lovelace Ada 2026/10/02
2. Ada Lovelace 02/10/2026
3. Ada Lovelace 2026/02/10
4. Ada Lovelace 10/02/2026

What does this log?

const text = "This is is a test of the the checker";
console.log(text.match(/\b(\w+) \1\b/g));

1. ["is", "the"]
2. ["This is", "of the"]
3. ["is is", "the the"]
4. null

What does this log?

const hex = /^#(?:[0-9a-f]{3}){1,2}$/i;
console.log(hex.test("#fff"), hex.test("#1A2b3C"), hex.test("#abcd"));

1. true true false
2. true false false
3. false true false
4. true true true

/a/ === /a/ is true because both regexes have the same pattern.

1. True
2. False