lib/stack.structures.js
function(){
            if(!this.size) return;
            var n = this.root, pr = n.previous, nx = n.next;
            if(this.size === 1){
                this.root = this.tail = null; this.size = 0;
                return n;
            } 
            nx.previous = pr; 
            delete this.root;
            this.root = nx;
            this.size -= 1;
            return n;
          }
function(){
            if(!this.size) return;
            var n = this.root, pr = n.previous, nx = n.next;
            if(this.size === 1){
                this.root = this.tail = null; this.size = 0;
                return n;
            } 
            nx.previous = pr; 
            delete this.root;
            this.root = nx;
            this.size -= 1;
            return n;
          }
function ( ) { if ( ! this . size ) return ; var n = this . root , pr = n . previous , nx = n . next ; if ( this . size === 1 ) { this . root = this . tail = null ; this . size = 0 ; return n ; } nx . previous = pr ; delete this . root ; this . root = nx ; this . size -= 1 ; return n ; }
pops of the root of the list
pops of the root of the list