defined-only-object

Javascript Library that will make it easy to find typo's when accessing object properties

The problem

Let's say you have a api like this.

var lightbulb = lightbulbFactory.getLightbulb(descriptor);

that returns an object like this:

var lightbulb =  {
turnOn: function() {...},
turnOff: function() {...},
isTurnedOn: true,
minimumPower : 12   //in Watts
}

There are some easy mistakes that can be made. For example, given the above 12 watt lightbulb that is turned on:

//alert if we are turned off
if(!lightbulb.isTunedOn) {
 alert("Turned Off")
}

// We only have 20 watts. make sure there is enough power to run this lightbulb
if(lightbulb.miniumPower < 20) {
 alert("Enough Power");
}
else alert("NOT ENOUGH POWER!");

Will alert "Turned Off" and "NOT ENOUGH POWER!". Surprised? Did you catch the typos?

> lightbulb.isTunedOn
undefined
>lightbulb.miniumPower
undefined

OOPS! Wouldn't it be great if Javascript could help us find silly typos? With this libary it can!

The Solution

import the library:

var DefinedOnlyObject = require('defined-only-object');
//or using fancy ES2016 syntax
import DefinedOnlyObject from 'defined-only-object';

then wrap any object with DefinedOnlyObject(); and be saved from hours of debugging!

var lightbulb = DefinedOnlyObject(lightbulbFactory.getLightbulb(descriptor));

Or better yet, if you're building an API, be nice to your users and return your objects already pre-wrapped.

function getLightbulb(descriptor) {
    ...
    return DefinedOnlyObject(result);

 }

Now if the user makes a typo like:

//alert if we are turned off
if(!lightbulb.isTunedOn) {
  alert("Turned Off")
}

// throws
> Uncaught isTunedOn is not a property of this object and would return undefined

Questions? Comments? More Features?

Open an issue or create a pull request