A simple implementation of wiggle sorting.

wiggle-sort.js

Array.prototype.wiggleSort = function() {
  for (let i = 0; i < this.length - 1; ++i) {
    const shouldNotBeLessThan = i % 2;
    const isLessThan = this[i] < this[i + 1];
    if (shouldNotBeLessThan && isLessThan) {
      [this[i], this[i + 1]] = [this[i + 1], this[i]];
    }
  }
  return this;
};