🔄 distinctUntilChanged() Polyfill

The distinctUntilChanged() method filters out consecutive duplicate values from an array, similar to the RxJS operator. It only removes duplicates that appear next to each other, preserving non-consecutive duplicates.

✅ Implementation

if (!Array.prototype.distinctUntilChanged) {
  Array.prototype.distinctUntilChanged = function () {
    const result = [];
    for (let i = 0; i < this.length; i++) {
      if (i === 0 || this[i] !== this[i - 1]) {
        result.push(this[i]);
      }
    }
    return result;
  };
}

Usage:

const arr = [1, 1, 2, 2, 2, 3, 1, 1];
const filtered = arr.distinctUntilChanged();
console.log(filtered); // [1, 2, 3, 1]