JavaScript · Junior · Question 57 of 75

What does this code print in a classic (non-strict) script?

let s = "cat";
s[0] = "b";
console.log(s);

✓Correct answer: cat
2bat
3It throws a TypeError

Explanation

Strings are immutable: index assignment is silently ignored (or throws in strict mode). Create a new string instead: "b" + s.slice(1).

Further reading

javascript.info: Strings ↗

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