Check whether all values are equal

Compare every item with the first using Object.is.

JavaScript Version 1.0.0 · MIT · .md

function allEqual(values) { return values.every(value => Object.is(value, values[0])); }

Input & expected output

[
  7,
  7,
  7
]

true

The edge case

[]

true

Know the limits

• The empty array returns true: no item violates the condition.
• Object.is distinguishes positive and negative zero. Objects use reference identity.

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

• Check whether an object is empty — Check for own enumerable string keys on a JSON object.
• Check whether an integer is even — Test parity for safe integers, including zero and negative values.
• Check a leap year — Apply the Gregorian divisible-by-4, century and 400-year rules.