Class: Observer

An observer manages a callback function

The update method is called with the subject object as this pointer. For this reason the callback should not be an arrow function, because it gets this pointer of its own context.

Include this class in your project with the following code:

import { Observer } from "@schukai/monster/source/types/observer.mjs";

The callback function is passed as the first argument to the constructor.

new Observer(()=>{
    // this is not subject
})

new Observer(function() {
    // this is subject
})

Additional arguments can be passed to the callback. To do this, simply specify them.

Observer(function(a, b, c) {
    console.log(a, b, c); // ↦ "a", 2, true
}, "a", 2, true)

The callback function must have as many parameters as arguments are given.

Constructor

new Observer(callback, …args)

Parameters:

Name	Type	Attributes	Description
`callback`	function
`args`	*	<repeatable>

Since: 1.0.0
Copyright: schukai GmbH
License: AGPLv3

Example

import {Observer} from '@schukai/monster/source/types/observer.mjs';

const observer = new Observer(function (a, b, c) {
    console.log(this, a, b, c); // ↦ "a", 2, true 
}, "a", 2, true);

observer.update({value: true}).then(() => {
});
// ↦ {value: true} "a" 2 true

Members

(static) instanceSymbol

This method is called by the instanceof operator.

Since: 2.1.0

Methods

addTag(tag) → {Observer}

Parameters:

Name	Type	Description
`tag`	string

Returns:

Type:: Observer

getTags() → {Array}

Returns:

Type:: Array

hasTag(tag) → {boolean}

Parameters:

Name	Type	Description
`tag`	string

Returns:

Type:: boolean

removeTag(tag) → {Observer}

Parameters:

Name	Type	Description
`tag`	string

Returns:

Type:: Observer

update(subject) → {Promise}

Parameters:

Name	Type	Description
`subject`	object

Returns:

Type:: Promise