How can I get a list of unique values in an array? Do I always have to use a second array or is there something similar to java\'s hashmap in JavaScript?
I am going
Using EcmaScript 2016 you can simply do it like this.
var arr = ["a", "a", "b"];
var uniqueArray = Array.from(new Set(arr)); // Unique Array ['a', 'b'];
Sets are always unique, and using Array.from() you can convert a Set to an array. For reference have a look at the documentations.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set