1 | # Emitter [![Build Status](https://travis-ci.org/component/emitter.png)](https://travis-ci.org/component/emitter)
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2 |
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3 | Event emitter component.
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4 |
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5 | ## Installation
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6 |
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7 | ```
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8 | $ component install component/emitter
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9 | ```
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10 |
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11 | ## API
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12 |
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13 | ### Emitter(obj)
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14 |
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15 | The `Emitter` may also be used as a mixin. For example
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16 | a "plain" object may become an emitter, or you may
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17 | extend an existing prototype.
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18 |
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19 | As an `Emitter` instance:
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20 |
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21 | ```js
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22 | var Emitter = require('emitter');
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23 | var emitter = new Emitter;
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24 | emitter.emit('something');
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25 | ```
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26 |
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27 | As a mixin:
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28 |
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29 | ```js
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30 | var Emitter = require('emitter');
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31 | var user = { name: 'tobi' };
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32 | Emitter(user);
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33 |
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34 | user.emit('im a user');
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35 | ```
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36 |
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37 | As a prototype mixin:
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38 |
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39 | ```js
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40 | var Emitter = require('emitter');
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41 | Emitter(User.prototype);
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42 | ```
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43 |
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44 | ### Emitter#on(event, fn)
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45 |
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46 | Register an `event` handler `fn`.
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47 |
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48 | ### Emitter#once(event, fn)
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49 |
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50 | Register a single-shot `event` handler `fn`,
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51 | removed immediately after it is invoked the
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52 | first time.
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53 |
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54 | ### Emitter#off(event, fn)
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55 |
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56 | * Pass `event` and `fn` to remove a listener.
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57 | * Pass `event` to remove all listeners on that event.
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58 | * Pass nothing to remove all listeners on all events.
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59 |
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60 | ### Emitter#emit(event, ...)
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61 |
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62 | Emit an `event` with variable option args.
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63 |
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64 | ### Emitter#listeners(event)
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65 |
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66 | Return an array of callbacks, or an empty array.
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67 |
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68 | ### Emitter#hasListeners(event)
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69 |
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70 | Check if this emitter has `event` handlers.
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71 |
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72 | ## License
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73 |
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74 | MIT
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