# observatoryjs

> Bind Object.observe events using mongo style querying.

Latest version **1.0.3** (published 2015-10-20) · MIT license · 0 weekly downloads

## Install

```sh
npm install observatoryjs
pnpm add observatoryjs
yarn add observatoryjs
bun add observatoryjs
```

## Health

**Score 15/100 (F)** — status: abandoned.

Positive: no vulnerabilities.

Warnings: low downloads; no types; no esm support.

Negative: abandoned; low maintenance score.

## Facts

| | |
|---|---|
| Version | 1.0.3 |
| Published | 2015-10-20 |
| First published | 2015-10-20 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | none |
| Module format | CommonJS |
| Dependencies | 0 |
| Known vulnerabilities | 0 |
| Install scripts | no |
| Author | mikesizz |
| Maintainers | mikesizz |

## Links

- npm: https://www.npmjs.com/package/observatoryjs
- Repository: https://github.com/mikesizz/observatory
- Issues: https://github.com/mikesizz/observatory/issues
- npm.io page: https://npm.io/package/observatoryjs

## Recent versions

- 1.0.3 (latest) — 2015-10-20
- 1.0.2 — 2015-10-20
- 1.0.1 — 2015-10-20
- 0.0.1 — 2015-10-20

## README

![http://vignette3.wikia.nocookie.net/zelda/images/0/03/Astral_Observatory.png/revision/latest?cb=20101108215818](http://vignette3.wikia.nocookie.net/zelda/images/0/03/Astral_Observatory.png/revision/latest?cb=20101108215818)

# Observatory

Observatory attempts to provide javascript developers an interface for [Object.observe](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/observe) with mongodb style querying for specificity.

## Installation

Observatory can be used in the browser as well as on the server via node.js.

	// bower
	bower install observatory

	// npm
	npm install observatoryjs


## Usage

Simply import the library, instantiate a new Observatory instance and start binding events. You can use simple, mongodb style querying to specify exactly when you want your callback to trigger. Think of it as a jQuery _on_ event binding, but for objects.

Below you can see a simple example of importing the library using the Commom.js standard, object instantiation and then finally a prototype of an event binding.

	// import library. Supports AMD, Common.js, and browser loading
	var Observatory = require("Observatory");

	// create Observatory instance
	var observer = new Observatory();

	// observation event structure
	observer.on( object , query , callback );

## Queries

Queries can be defined in two different ways. You can either specify an object property to observe or you can create a expression for more granular observations.

	observer.on( obj , { event: property } , callback );

		// or

	observer.on( obj , { event: {expression} } , callback );

Note that you can replace the object property in the first example with the wildcard character '*' to observe events for all object properties.

### Events

The currently supported events are listed below. More events will be added in future releases.

* **$update** - observe events that include an update to a queried property
* **$add** - observe events that include an addition to a queried property
* **$delete** - observe events that include an deletion from a queried property

### Expressions

By using different selectors you can create an expression for more specific event handling. Below is a prototypical example of an expression in action, as well as a list of the different types of selectors you can use with examples for each. 

	observer.on( obj , { event: { property: { selector: parameter } } } , callback );

#### Value Selectors

**$gt** - check if the property is greater than the query value

	var cat = {
		age: 3
	};

	observer.on( cat , { $update: { "age": { $gt: 10 } } } , function(){
		console.log("that cat is older than 10");
	});	

**$lt** - check if the property is less than the query value

	var cat = {
		age: 3
	};

	observer.on( cat , { $update: { "age": { $lt: 10 } } } , function(){
		console.log("that cat is younger than 10");
	});	

**$gte** - check if the property is greater than or equal to the query value

	var cat = {
		age: 3
	};

	observer.on( cat , { $update: { "age": { $gte: 10 } } } , function(){
		console.log("that cat is old!");
	});	

**$lte** - check if the property is less than or equal to the query value

	var cat = {
		age: 3
	};

	observer.on( cat , { $update: { "age": { $lte: 9 } } } , function(){
		console.log("that cat is young.");
	});	

**$eq** - check if the property is equal to the query value

	var cat = {
		age: 3
	};

	observer.on( cat , { $update: { "age": { $eq: 10 } } } , function(){
		console.log("that cat is 10");
	});

#### Array Selectors

**$in** - check if the target array contains any of the query values after the event fires
 
	var foo = {
		languages: [ "c++" , "c" , "java" ]
	};

	observer.on( foo , { $add: { "languages": { $in: [ "javascript" , "lua" ] } } } , function(){ 
		console.log("no scripting allowed!"); 
	});

**$all** - check if the target array contains all of the query values after the event fires

	var foo = {
		languages: [ "c++" , "c" , "java" ]
	};

	observer.on( foo , { $add: { "languages": { $all: [ "c" , "c++" , "c#" ] } } } , function(){ 
		console.log("much c!"); 
	});	

## Depth

You can observe as far as top level properties of objects that are nested within the observed object. This can be achieved by using object dot notation, wrapped in quotes, in your observation queries.
	
	var obj = {
		foo:{
			bar: "gg m8" // you can observe this far
		}
	}

	observer.on( obj , { $update: "foo.bar" } , callback );

### Notes:

* From the context of within the callback body, _this_ is set to the observed object.
* The events array is always passed into the callback as the first and only argument.

---
_Source: https://npm.io/package/observatoryjs · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._