# List
> **API Reference** ▸ **List**
Access it with:
```javascript
const { List } = Neft;
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/list/index.litcoffee)
* * *
### `constructor()`
- Parameters
Creates a new list instance.
```javascript
var list = new List([1, 2]);
list instanceof List; // true
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/list/index.litcoffee#listconstructorarray-data)
* * *
### `onChange()`
- Parameters
- oldValue — Any
- index — Integer
- Type
- Signal
Signal called on each value change.
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/list/index.litcoffee#signal-listonchangeany-oldvalue-integer-index)
* * *
### `onInsert()`
- Parameters
- value — Any
- index — Integer
- Type
- Signal
Signal called when a value was added.
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/list/index.litcoffee#signal-listoninsertany-value-integer-index)
* * *
### `onPop()`
- Parameters
- oldValue — Any
- index — Integer
- Type
- Signal
Signal called when a value was removed.
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/list/index.litcoffee#signal-listonpopany-oldvalue-integer-index)
* * *
### `length`
- Type
- Integer
- Read Only
Amount of values stored in the list.
```javascript
var list = new List(['a', 'b']);
list.length; // 2
```
* * *
### `set()`
- Parameters
- index — Integer
- value — Any
- Returns
- Any
Sets the given value under the given index.
The index must exists in the list.
The value can't be an `undefined`. Use `pop()` instead.
Calls `onChange()` signal.
```javascript
var types = new List(['fantasy', 'Thriller']);
types.onChange.connect(function(oldVal, i){
console.log("element "+oldVal+" changed to "+this[i]);
});
types.set(0, 'Fantasy');
// element fantasy changed to Fantasy
types.set(0, 'Fantasy');
// nothing changed ...
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/list/index.litcoffee#any-listsetinteger-index-any-value)
* * *
### `append()`
- Parameters
- Returns
- Any
Adds the given value on the end on the list.
The value can't be an `undefined`.
Calls `onInsert()` signal.
```javascript
var fridge = new List(['apple', 'milk']);
fridge.onInsert.connect(function(val, i){
console.log(val+" appended!");
});
fridge.append('cheese');
// cheese appended!
console.log(fridge.items());
// apple, milk, cheese
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/list/index.litcoffee#any-listappendany-value)
* * *
### `insert()`
- Parameters
- index — Integer
- value — Any
- Returns
- Any
Add the given value under the given index.
The index can't be greater than the list length.
The value can't be an `undefined`.
Calls `onInsert()` signal.
```javascript
var list = new List(['a', 'b']);
list.onInsert.connect(function(val, i){
console.log("new element "+val+" inserted at index "+i);
});
list.insert(1, 'c');
// new element c inserted at index 1
console.log(list.items());
// ['a', 'c', 'b']
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/list/index.litcoffee#any-listinsertinteger-index-any-value)
* * *
### `extend()`
- Parameters
- Returns
- List
Appends all values stored in the given items into the list.
Calls `onInsert()` signal for each value.
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/list/index.litcoffee#list-listextendobject-items)
* * *
### `remove()`
- Parameters
- Returns
- Any
Removes the given value from the list.
Calls `onPop()` signal.
```javascript
var list = new List(['a', 'b']);
list[1]; // b
list.remove('b');
list[1]; // undefined
list; // ['a']
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/list/index.litcoffee#any-listremoveany-value)
* * *
### `pop()`
- Parameters
- index — Integer — optional
- Returns
- Any
Removes the value stored in the list under the given index.
The index must exists in the list.
Calls `onPop()` signal.
```javascript
var list = new List(['a', 'b']);
list[1]; // b
list.pop(1);
list[1]; // undefined
list; // ['a']
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/list/index.litcoffee#any-listpopinteger-index)
* * *
### `clear()`
Removes all values stored in the list.
Calls `onPop()` signal for each value.
```javascript
var list = new List(['a', 'b']);
list.onPop.connect(function(oldVal, i){
console.log("Element "+oldVal+" popped!");
});
console.log(list.items());
// ['a', 'b']
list.clear()
// Element b popped!
// Element a popped!
console.log(list);
// []
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/list/index.litcoffee#listclear)
* * *
### `index()`
- Parameters
- Returns
- Integer
Returns the given value index in the list.
Returns `-1` if the value doesn't exist in the list.
```javascript
var list = new List(['a', 'b']);
list.index('b'); // 1
list.index('c'); // -1
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/list/index.litcoffee#integer-listindexany-value)
* * *
### `has()`
- Parameters
- Returns
- Boolean
Returns `true` if the given value exists in the list.
```javascript
var list = new List(['a', 'b']);
list.has('a'); // true
list.has('ab123'); // false
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/list/index.litcoffee#boolean-listhasany-value)
* * *
### `toArray()`
- Returns
- Array
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/list/index.litcoffee#array-listtoarray)