> [Wiki](Home) ▸ [[API Reference|API-Reference]] ▸ **Dict**
# Dict
> data-binding for objects
Access it with:
```javascript
const { Dict } = Neft
```
> [`Source`](/Neft-io/neft/blob/e79ebc2b61607e795a53c22d1577605addf00689/src/dict/index.litcoffee)
## Table of contents
* [Dict](#dict)
* [**Class** Dict](#class-dict)
* [fromJSON](#fromjson)
* [constructor](#constructor)
* [length](#length)
* [onChange](#onchange)
* [set](#set)
* [has](#has)
* [extend](#extend)
* [pop](#pop)
* [clear](#clear)
* [keys](#keys)
* [values](#values)
* [items](#items)
* [Iterate over a dict](#iterate-over-a-dict)
* [Glossary](#glossary)
# **Class** Dict
> [`Source`](/Neft-io/neft/blob/e79ebc2b61607e795a53c22d1577605addf00689/src/dict/index.litcoffee)
##fromJSON
- Syntax
*Dict* Dict.fromJSON(*String*|*Object* json)- Static method of
- Dict
- Parameters
- Returns
- Dict
Creates a new [Dict](/Neft-io/neft/wiki/Dict-API#class-dict) from a json string.
This function should be used with `toJSON()` output.
> [`Source`](/Neft-io/neft/blob/e79ebc2b61607e795a53c22d1577605addf00689/src/dict/index.litcoffee#dict-dictfromjsonstringobject-json)
##constructor
- Syntax
Dict::constructor([*Object* data])- Prototype method of
- Dict
- Parameters
Creates a new dict instance.
The given data parameter determines default keys with their values.
```javascript
var data = new Dict({
name: 'xyz'
});
data.name; // xyz
```
> [`Source`](/Neft-io/neft/blob/e79ebc2b61607e795a53c22d1577605addf00689/src/dict/index.litcoffee#dictconstructorobject-data)
##length
- Syntax
ReadOnly *Integer* Dict::length- Prototype property of
- Dict
- Type
- Integer
- Read Only
Amount of keys stored in a dict.
```javascript
var dict = Dict({prop: 1});
dict.length; // 1
```
> [`Source`](/Neft-io/neft/blob/e79ebc2b61607e795a53c22d1577605addf00689/src/dict/index.litcoffee#readonly-integer-dictlength)
##onChange
- Syntax
*Signal* Dict::onChange(*String* key, *Any* oldValue)- Prototype method of
- Dict
- Parameters
- key — String
- oldValue — Any
- Type
- Signal
Signal called on each key value change.
```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`](/Neft-io/neft/blob/e79ebc2b61607e795a53c22d1577605addf00689/src/dict/index.litcoffee#signal-dictonchangestring-key-any-oldvalue)
##set
- Syntax
*Any* Dict::set(*String* key, *Any* value)- Prototype method of
- Dict
- Parameters
- Returns
- Any
Sets the given value for the given key stored in the dict.
The value can't be an undefined. Use `pop()` instead.
Calls `onChange()` signal.
```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`](/Neft-io/neft/blob/e79ebc2b61607e795a53c22d1577605addf00689/src/dict/index.litcoffee#any-dictsetstring-key-any-value)
##has
- Syntax
*Boolean* Dict::has(*String* key)- Prototype method of
- Dict
- Parameters
- Returns
- Boolean
Returns `true` if the given key exists in the dict.
> [`Source`](/Neft-io/neft/blob/e79ebc2b61607e795a53c22d1577605addf00689/src/dict/index.litcoffee#boolean-dicthasstring-key)
##extend
- Syntax
*Dict* Dict::extend(*Object*|*Dict* object)- Prototype method of
- Dict
- Parameters
- Returns
- Dict
Sets all keys with their values from the given object.
Calls `onChange()` signal for each key.
> [`Source`](/Neft-io/neft/blob/e79ebc2b61607e795a53c22d1577605addf00689/src/dict/index.litcoffee#dict-dictextendobjectdict-object)
##pop
- Syntax
*Any* Dict::pop(*String* key)- Prototype method of
- Dict
- Parameters
- Returns
- Any
Removes the given key from the dict.
The key must exists in the dict.
Calls `onChange()` signal.
```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`](/Neft-io/neft/blob/e79ebc2b61607e795a53c22d1577605addf00689/src/dict/index.litcoffee#any-dictpopstring-key)
##clear
- Syntax
Dict::clear()- Prototype method of
- Dict
Removes all stored keys from the dict.
Calls `onChange()` signal for each stored key.
> [`Source`](/Neft-io/neft/blob/e79ebc2b61607e795a53c22d1577605addf00689/src/dict/index.litcoffee#dictclear)
##keys
- Syntax
ReadOnly *Array* Dict::keys()- Prototype method of
- Dict
- Returns
- Array
- Read Only
Returns an array of keys stored in the dict.
Always returns the same array instance.
```javascript
var data = new Dict({
x: 10,
y: 30
});
data.keys(); // ['x', 'y']
```
> [`Source`](/Neft-io/neft/blob/e79ebc2b61607e795a53c22d1577605addf00689/src/dict/index.litcoffee#readonly-array-dictkeys)
##values
- Syntax
*Array* Dict::values()- Prototype method of
- Dict
- Returns
- Array
Returns an array of values stored in the dict.
Always returns the same array instance.
```javascript
var data = new Dict({
x: 10,
y: 30
});
data.values(); // [10, 30]
```
> [`Source`](/Neft-io/neft/blob/e79ebc2b61607e795a53c22d1577605addf00689/src/dict/index.litcoffee#array-dictvalues)
##items
- Syntax
*Array* Dict::items()- Prototype method of
- Dict
- Returns
- Array
Returns an array of key-value pairs stored in the dict.
Always returns the same array instance.
```javascript
var data = new Dict({
x: 10,
y: 30
});
data.items(); // [['x', 10], ['y', 30]]
```
### Iterate over a dict
```javascript
var dict = new Dict({prop1: 1, prop2: 2});
var items = dict.items();
for (var i = 0; i < items.length; i++){
console.log(items[i][0], items[i][1]);
}
// ['prop1', 1]
// ['prop2', 2]
```
> [`Source`](/Neft-io/neft/blob/e79ebc2b61607e795a53c22d1577605addf00689/src/dict/index.litcoffee)
# Glossary
- [Dict](#class-dict)