Get the unique values of an array

Keep the first occurrence of each value with a Set.

JavaScript Version 1.0.0 · MIT · .md

function uniqueValues(values) { return [...new Set(values)]; }

Input & expected output

[
  "delivered",
  "deferred",
  "delivered"
]

[
  "delivered",
  "deferred"
]

The edge case

[
  null,
  null,
  0
]

[
  null,
  0
]

Know the limits

• Same idea as Remove duplicate values; SameValueZero treats NaN as equal to NaN.

The function above is the implementation used by the lab. The lab validates JSON types and caps size before execution; include equivalent validation when accepting untrusted input in your application.

Keep exploring

• Clone an array — Create a new array without copying the objects inside it.
• Remove duplicate values — Keep the first occurrence of each value, in its original order.
• Flatten a nested array — Turn a nested array into one sequence of values.