linked-list.js

// https://en.wikipedia.org/wiki/Linked_list
// https://blog.jcoglan.com/2007/07/23/writing-a-linked-list-in-javascript/

// Reducible prototype for linked list node.
var __node__ = {
  reduce: function reduceNodes(reducer, initial) {
    var node = this;
    var accumulated = initial;
    do {
      accumulated = reducer(accumulated, node);
      node = next(node);
    }
    while(node !== null);
    return accumulated;
  }
};

// Create a linked list node.
function node(value, nextNode) {
  // Create new node object.
  var n = Object.create(__node__);
  // Assign value and next.
  n.value = value;
  n.next = nextNode;
  return n;
}

function next(node) {
  return node && node.next ? node.next : null;
}

function value(node) {
  return node && node.value ? node.value : null;
}

// Given 2 items, return second.
function chooseCurr(prev, curr) {
  return curr;
}

// Find head of reducible data structure.
function head(reducible) {
  return reducible.reduce(chooseCurr);
}

// Find first matching node for `predicate` in reducible
// data structure.
function find(reducible, predicate) {
  return reducible.reduce(function reduceFind(found, node) {
    // Match values, not nodes. This allows for general-purpose
    // predicate functions.
    if (found) return found;
    if (predicate(value(node))) return node;
    return null;
  }, null);
}