Which answer is correct?

Use `[...new Set(array)]`. Set only keeps unique values, spread converts it back to an array.

— es6_lover

Use `array.filter((v, i) => array.indexOf(v) === i)`. Keeps only the first occurrence.

— functional_fan

Use `Array.from(new Set(array))`. Same as spread but more explicit.

— readability_first

Use a for loop with `includes()` check and push to a new array.

— traditional_js