# Dict
> **API Reference** ▸ **Dict**
Access it with:
```javascript
const { Dict } = Neft
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/dict/index.litcoffee)
* * *
### `Dict.fromJSON()`
- Static method of
- Dict
- Parameters
- Returns
- Dict
Returns a new *Dict* based on the given *json*.
Example:
```javascript
const dict = Dict.fromJSON('{"param": "value"}');
dict.param; // value
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/dict/index.litcoffee#dict-dictfromjsonstringobject-json)
* * *
### `constructor()`
- Parameters
Creates a new dict instance.
The given *data* parameter determines default keys with their values.
Example:
```javascript
var data = new Dict({
name: 'xyz'
});
data.name; // xyz
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/dict/index.litcoffee#dictconstructorobject-data)
* * *
### `length`
- Type
- Integer
- Read Only
Returns an amount of keys stored in this *Dict*.
This property cannot be changed manually.
Example:
```javascript
var dict = Dict({ prop: 1 });
dict.length; // 1
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/dict/index.litcoffee#readonly-integer-dictlength)
* * *
### `onChange()`
- Parameters
- key — String
- oldValue — Any
- Type
- Signal
Signal called on each key value change.
Example:
```javascript
var user = new Dict({
country: 'Germany'
});
user.onChange.connect(function(key, oldVal){
console.log(key + " property changed from " + oldVal + " to " + this[key]);
});
user.set('country', 'US');
// country property changed from Germany to US
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/dict/index.litcoffee#signal-dictonchangestring-key-any-oldvalue)
* * *
### `set()`
- Parameters
- Returns
- Any
Sets the given value under the given key in this *Dict*.
The given value can't be an undefined. Use `pop()` instead.
Calls `onChange()` signal.
Example:
```javascript
var links = new Dict({
facebook: 'https://facebook.com/neft.io',
twitter: 'https://twitter.com/neft_io'
});
links.onChange.connect(function(key, oldVal){
console.log(key + " changed from " + oldVal + " to " + this[key]);
});
links.set('googlePlus', 'https://plus.google.com/+NeftIo-for-apps/');
// googlePlus changed from undefined to https://...
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/dict/index.litcoffee#any-dictsetstring-key-any-value)
* * *
### `has()`
- Parameters
- Returns
- Boolean
Returns `true` if the given key exists in this *Dict*.
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/dict/index.litcoffee#boolean-dicthasstring-key)
* * *
### `extend()`
- Parameters
- Returns
- Dict
Sets all keys with their values from the given object into this *Dict*.
Calls `onChange()` signal for each given key.
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/dict/index.litcoffee#dict-dictextendobjectdict-object)
* * *
### `pop()`
- Parameters
- Returns
- Any
Removes the given key from this *Dict*.
The given key must exists.
Calls `onChange()` signal.
Example:
```javascript
var data = new Dict;
data.set('name', 'John');
data.onChange.connect(function(key, oldVal){
if (this[key] === undefined){
console.log(key + " property has been removed");
}
});
data.pop('name');
// name property has been removed
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/dict/index.litcoffee#any-dictpopstring-key)
* * *
### `clear()`
Removes all stored keys from this *Dict*.
Calls `onChange()` signal for each stored key.
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/dict/index.litcoffee#dictclear)
* * *
### `keys()`
- Returns
- Array
- Read Only
Returns an array of keys stored in this *Dict*.
Returned array is *read only* and cannot be modified.
Always returns the same array instance.
Example:
```javascript
var data = new Dict({
x: 10,
y: 30
});
data.keys(); // ['x', 'y']
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/dict/index.litcoffee#readonly-array-dictkeys)
* * *
### `values()`
- Returns
- Array
Returns an array of values stored in this *Dict*.
Returned array is *read only* and cannot be modified.
Always returns the same array instance.
Example:
```javascript
var data = new Dict({
x: 10,
y: 30
});
data.values(); // [10, 30]
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/dict/index.litcoffee#array-dictvalues)
* * *
### `items()`
- Returns
- Array
Returns an array of key-value pairs stored in this *Dict*.
Returned array is *read only* and cannot be modified.
Always returns the same array instance.
Example:
```javascript
var data = new Dict({
x: 10,
y: 30
});
data.items(); // [['x', 10], ['y', 30]]
```
> [`Source`](https://github.com/Neft-io/neft/blob/f9c128ccb37aa79380c961e878cd76ec9e79c99e/src/dict/index.litcoffee#array-dictitems)