react-native-general-listener

中文说明

It is a wrapper of DeviceEventListener to support following functions:

• Event level to make event name more readable.
• Subscribe all sub level event and unsubscribe.

Install

Install by Yarn:

yarn add react-native-general-listener

Install by NPM:

npm install --save react-native-general-listener

Usage

Import the module in file:

import Listener from 'react-native-general-listener';

Then you can register, unregister or trigger an event type.

Event Type Structure

An event type can be a string, an array of string, or an object.

• a string: Use the string as event name directly, it is not supported to trigger parent or child event.
• an array of string: We will use seperator to connect these strings to generate event name. And you can register with listen to its child event, or trigger its parent event.
• an object: Use the json string of object as event name. We do not recommend this usage.

Register

We have two register function:

• register
• registerWithSubEvent

They both have two parameters:

• type: Event type.
• func: Event callback, will be called when the event is triggered.

Example:

this.loginListener1 = Listener.register('LoginEvent', this.loginFn);
this.loginListener2 = Listener.register(['TestApp', 'Login', userId], this.loginFn);

The only difference between register and registerWithSubEvent is: the second one register event type with all sub level event types.

The function will return an object to used when unregister event type.

Unregister

You can unregister one event listener or all of an event type.

The function unregister has three parameters:

• type: Event type.
• listenerObj: Listener object which is the returned value of register or registerWithSubEvent. If it is undefined, we will remove all event listeners of the event type.

Example:

Listener.unregister('LoginEvent', this.loginListener1);
Listener.unregister('LoginEvent');
Listener.unregister(['TestApp', 'Login', userId], this.loginListener);
Listener.unregister(['TestApp', 'Login', userId]);

Trigger

You can trigger event with an event type and an event param.

The function trigger has three parameters:

• type: Event type.
• state: Event param. It can be an object, a number, a boolean or any other data type.

When trigger an event with an array of string event type [str0, str1, ... strn], we will find its parent event types to see if they use registerWithSubEvent function:

const upperType = [str0, str1, ..., strn];
while ( /* upperType is not empty */ ) {
    // Convert upperType to upperName
    if ( /* upperName is registered with registerWithSubEvent function */ ) {
        // Trigger upper event with state
    }
    // Pop the last element of upperType
}

Global Constant

There are two constant in the module:

• defaultSeperator: Default seperator, used as connector of event type to generate event name. Default is '$'。
• innerEventType: Inner event type key, when event is triggered, the event type will be set into event param if event param is an object. This key is '_##_inner_##_event_##_type_##_' to avoid key duplication in event param.

You can modify them globally:

Listener.defaultSeperator = '#';
Listener.innerEventType = '123321';