Last Result Used

lru.js

function LRU(limit) {
    this.limit = limit || 1000;
    this.map = new Map();
}

LRU.prototype.has = function(key) {
    return this.map.has(key);
}

LRU.prototype.set = function(key, value) {
  this.map.delete(key);
  this.map.set(key, value);
  if ( this.map.size > this.limit ) {
    this.map.delete( this.map.keys().next().value );
  }
  return this;
};

LRU.prototype.get = function(key) {
  if ( this.map.has(key) ) {
    var value = this.map.get(key);
    this.map.delete(key);
    this.map.set(key, value);
    return value;
  }
};

LRU.prototype.clear = function() {
  this.map.clear();
};

Why are you re-setting the value on the map, lines 22-23?