Check if all array elements are equal to a given value

JavaScript

const isEqual = (arr, value) => arr.every((item) => item === value)

// Or
// Ends earlier for false arrays
const isEqual = (arr, value) => !arr.some((item) => item !== value)

Examples

isEqual(['foo', 'foo'], 'foo') // true
isEqual(['foo', 'bar'], 'foo') // false
isEqual(['bar', 'bar'], 'foo') // false