Functions to check for, or remove duplicate array items.
var notDupe = require('dupe')
var isDupe = require('dupe/isDupe')
var duplicates = [1, 2, 1, 3, 4, 1, 3, 4, 'five', 2, 6]
var originals = [4, 8, 15, 16, 23, 42]
// Remove duplicates:
console.log( duplicates.filter( notDupe ) ) // => [1, 2, 3, 4, 'five', 6]
console.log( originals.filter( notDupe ) ) // => [4, 8, 15, 16, 23, 42]
// Assert the lack of duplicates:
console.log( duplicates.every( notDupe ) ) // => false
console.log( originals.every( notDupe ) ) // => true
// Remove originals:
console.log( duplicates.filter( isDupe ) ) // => [1, 1, 3, 4, 2]
console.log( originals.filter( isDupe ) ) // => []
// Assert the presence of duplicates:
console.log( duplicates.some( isDupe ) ) // => true
console.log( originals.some( isDupe ) ) // => false
With npm do:
npm install dupe