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1.0.0 • Public • Published


Wraps any list-like object with an interface containing a full set of superpowered, chainable list methods, including toggle, replace, etc.


Requires Node.js 6.0.0 or above.

npm i listwrap


The module exports a single class. The constructor expects an object argument with 6 function properties: add, remove, has, values, item, and length. These are the 6 foundational functions which Listwrap combines to produce new functions like toggle and replace. The object argument may optionally also include the optional methods removeAll and/or sanitize.

The following example makes use of Listwrap to extend the basic JavaScript array with new methods:

const Listwrap = require('listwrap')
const vdel = require('vdel')
class SuperArray extends Listwrap {
  constructor () {
    const array = []
      add: v => { array.push(v) },
      remove: v => { vdel(array, v) },
      has: v => array.includes(v),
      values: () => array,
      item: i => array[i],
      length: () => array.length,
const super = new SuperArray()
super.add(1, 2, 3)
  .toggle(1) // Removes 1 if present
  .replace(3, 4) // Replaces 3 with 4
  .hasAny(4, 5) // Returns true, since one of the arguments (4) is present
super.values() // [2, 4]


In the function definitions below, the ...items parameter is a rest parameter that will accept any number of arguments.

  • constructor (methods)
    • methods: An object containing the underlying methods for the list:
      • Required functions: add, remove, has, values, item, and length.
      • Optional functions: removeAll and sanitize.
  • has (...items)
    • Will return true only if all items are present.
  • hasAny (...items)
    • Will return true if at least one item is present.
  • add (...items)
  • remove (...items)
  • removeIf (callback)
  • removeAll()
  • removeAllExcept (...permittedValues)
  • replace (oldItems, newItems)
    • oldItems: A value or an array of values.
    • newItems: A value or an array of values.
    • If all the oldItems are present, they are removed and replaced with newItems.
  • toggle (...items)
    • For each given item, removes it if it’s present, and adds it if not. Each item is toggled independently of the others.
  • toggleTogether (...items)
    • If all given items are present, removes all of them. Otherwise adds any that are not present. Ensures that no item is present or absent without the others.
  • if (condition, thenItems, [elseItems])
    • condition: A boolean that determines whether or not the items should be present.
    • thenItems: A value or an array of values.
    • elseItems: A value or an array of values.
    • If condition is true, removes elseItems and adds thenItems. Otherwise removes themItems and adds elseItems.
  • item (index)
  • length


npm i listwrap

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