NullSafe

A null safety utility for objects and nested arrays in Javascript

This package will allow you to safely access and set properties on nested objects and arrays with throwing everyone"s favorite error: "Cannot read property ___ of undefined"

To Install

1. install the package: npm install @mrkutly/null-safe

2. require it in your package:

   const ns = require('@mrkutly/null-safe');

To Use

Note: in versions prior to 1.1.0, ns was just a getter function. In 1.1.0 and above, ns is an object with a get() function and a set() function.

Getting values

The ns.get() function takes in 2 arguments: the object you want to access and a string of accessors.

ns.get(object, accessors);

For example:

const butter = {
	milk: 'cow',
	colors: [['yellow'], 'white', 'cream'],
	price: {
		denomination: 'USD',
		amount: 200,
		tax: {
			state: 10,
			federal: 20,
		},
	},
	info: {
		'date-churned': 'October 1st',
	},
};

ns.get(butter, 'price.tax.state'); // = 1;
ns.get(butter, 'colors[0][0]'); // => "yellow";
ns.get(butter, 'some.null.value'); // => undefined;

The accessors you pass are just whatever accessors you would normally use in js assuming all of the values in the chain are not undefined or null. If any of the values in the chain evaluate to undefined, ns.get() will return undefined rather than throwing an error.

If using a key with a "-", do not wrap it in quotes like you normally would. Instead just do this:

ns.get(butter, 'info[date-churned]'); // => October 1st;

Setting Values

The ns.get() function takes in 3 arguments: the object you want to access, a string of accessors, and the value you want to set the last accessor key to.

const butter = {
	milk: 'cow',
	colors: [['yellow'], 'white', 'cream'],
	price: {
		denomination: 'USD',
		amount: 200,
		tax: {
			state: 10,
			federal: 20,
		},
	},
	info: {
		'date-churned': 'October 1st',
	},
};

ns.set(butter, 'price.tax.state', 'one billion dollars');
// => 'one billion dollars'
// butter.price.tax.state => "one billion dollars";
ns.set(butter, 'colors[0][0]', 'marigold');
// => "marigold";
// butter.colors[0][0] => "marigold";
ns.set(butter, 'some.null.value', 'something');
// => undefined
// => nothing happens;

The accessors you pass are just whatever accessors you would normally use in js assuming all of the values in the chain are not undefined or null. If any of the values in the chain evaluate to undefined, ns.set() will return undefined and will not have a side effect on the object.

If using a key with a "-", do not wrap it in quotes like you normally would. Instead just do this:

ns.set(butter, 'info[date-churned]', 'January 1st');
// => January 1st;
// butter.info["date-churned"] => "January 1st"

Calling Methods

The ns.call() function takes in 2 required arguments and any number of optional arguments: the object you want to call the method on, a string of accessors to the method you want to call, and (optional) any arguments you want to call the method with.

function sayPhrase(exclamation = '', extra = '') {
	return this.phrase + exclamation + extra;
}

const person = {
	name: 'mark',
	sayHello() {
		return 'hello';
	},
	sayHelloWithName(name) {
		return 'hello ' + name;
	},
	sayHelloWithThis() {
		return "hi i'm " + this.name;
	},
	birthplace: {
		city: 'Dallas',
		state: 'Texas',
		introduce() {
			return `My name is mark and I was born in ${this.city}, ${this.state}.`;
		},
	},
	favoritePhrases: [
		{
			phrase: 'I love dogs',
			sayPhrase,
			variations: [
				{
					phrase: 'I love doggos',
					sayPhrase,
				},
			],
		},
		{
			phrase: 'Pizza is great',
			sayPhrase,
			variations: [
				{
					phrase: 'L&B is the best',
					sayPhrase,
				},
			],
		},
		{
			phrase: 'Sick!',
			sayPhrase,
			variations: [
				{
					phrase: "That's so sick",
					sayPhrase,
				},
			],
		},
	],
};

ns.call(person, 'sayHelloWithThis'); // => "hi i'm mark"
ns.call(person, 'favoritePhrases[0].variations[0].sayPhrase'); // => 'I love doggos'
ns.call(person, 'favoritePhrases[1].sayPhrase', '!'); // => "Pizza is great!";
ns.call(person, 'someFakeMethod'); // => undefined

The accessors you pass are just whatever accessors you would normally use in js assuming all of the values in the chain are not undefined or null. If any of the values in the chain evaluate to undefined, ns.call() will return undefined and will not have a side effect on the object.

If using a key with a "-", do not wrap it in quotes like you normally would. Instead just do this:

ns.call(person, '[some-key]', 'some argument');