linked.js

class ListNode {
    constructor(data) {
        this.data = data
        this.next = null                
    }
}

class LinkedList {
    constructor(head = null) {
        this.head = head
    }
}

let node1 = new ListNode(2)
let node2 = new ListNode(5)
node1.next = node2

var list = new LinkedList(node1)


function searchLL(list, item) {
    var temp = list.head;
    while (temp !== null) {
        if(temp.data === item) {
            return true;
        }

        temp = temp.next;
    }
    return false
}

searchLL(list, 4)