Untitled

<!DOCTYPE html>
<html>
<head>
	<title>TEST</title>
</head>
<body>
	<script>
	class LinkedList{
		constructor(){
			this.list = null;
		}

		push(item){
			this.list = {value: item, next: this.list};
		}

		pop(){
			var {value: item} = this.list;
			this.list = this.list.next != null ? { value: this.list.next.value, next: this.list.next.next} : {value : null};
			return item;
		}
		unshift(x) {
		    let current = this.list;
		    if (current) {
		      while(current.next){
		        current = current.next;
		      }
		      current.next = {value : x, next : null};
		    }else{
			  this.list = {value: x, next: this.list};
		    }
		  }
		shift() {
		    let current = this.list;
		    let previous = {};
		    while(current.next){
		      previous = current;
		      current = current.next;
		    }
		    let {value : lastEle} = current;
		    previous.next = null;
		    current = previous;
		    return lastEle;
		  }
		 count() {
		    let count = 0;
		    var elements = this.list;
		    while(elements){
		        count++;
		        elements = elements.next;
		    }
		    return count;
		  }
		}

	var list1 = new LinkedList();
	list1.push(31);
	list1.unshift(43);
	list1.shift();
	list1.pop();
	console.log(list1.list);
	console.log(list1.count());

	</script>
</body>
</html>