ABANDONED 4/22/2016 Object.observe has been removed from future versions of V8. Therefore, this module is no longer being maintained.

Bind Json - "bjson"

Bind Json: Reactive way to read/write json files.

Note:
Bind Json, called as "bjson", don't have ANY RELATIONS with Binary Json, also called as "bjson".
These are two different projects with same abbreviation name. Sorry for this.

How it works

When you need to edit a json file, what you do?

Examples

Editing .json file without bjson

var fs = require('fs');
if(!fs.existsSync('settings.json')){
  fs.writeFileSync('settings.json', '{}');
}
var settingsJson = fs.readFileSync('settings.json');
var settings = JSON.parse(settingsJson);
settings.foo = 'bar';
var settingsJson = JSON.stringify(settings, null, 2);
fs.writeFileSync('settings.json', settingsJson);

Editing .json file with bjson

var bjson = require('bjson');
var settings = bjson('settings.json');
settings.foo = 'bar'; 

Getting started

Binding json

settings.json

{}

whatever.js

var bjson = require('bjson');
var settings = bjson('settings'); // will read or create settings.json
settings.prop = 'bar';

settings.json:

{
    "prop": "bar"
}

Watching changes with observe

You can watch changes with a instance of Object.observe passed as callback argument.

settings.json:

{
    "prop": "bar"
}

whatever.js

var bjson = require('bjson');
var settings = bjson('settings', function(observe){
    observe.on('change', function(changes){
        console.log('Path:', changes.path);
        console.log('Old Value:', changes.oldValue);
        console.log('New Value:', changes.value);
        console.log('-----');
    });
});

settings.prop = 'foo';
settings.otherprop = 'bar';

Log output:

Path: prop
Old Value: bar
New Value: foo
-----
Path: otherprop
Old Value: undefined
New Value: bar
-----

settings.json:

{
    "prop": "foo",
    "otherprop": "bar"
}

Observe events

var bjson = require('bjson');
var settings = bjson('settings', function(observe){
    observe.on('add', function(changes){});
    observe.on('update', function(changes){});
    observe.on('delete', function(changes){});
    observe.on('reconfigure', function(changes){});
    observe.on('change', function(changes){}); // fired when any of the above events are emitted
});

Observe events callback changes

path: full path to the property, including nesting
name: name of the path
type: name of the event
object: object
value: current value for the given path. same as object[name]
oldValue: previous value of the property

Example:

var bjson = require('bjson');
var settings = bjson('settings', function(observe){
    observe.on('change', function(changes){
        console.log(changes);
    });
});

settings.foo = 'bar'

//log:
// { path: 'foo',
//   name: 'foo',
//   type: 'add',
//   object: { foo: 'bar' },
//   value: 'bar',
//   oldValue: undefined }