trapcodeio/proxy-undefined

Proxify javascript values to return a default value if undefined.

ProxyUndefined

Return default value for object properties that does not exists i.e is undefined.

Install

npm install proxy-undefined

yarn add proxy-undefined

Usage

const {optional, optionalFn} = require("proxy-undefined");
// Or
import {optional, optionalFn} from "proxy-undefined";

Why ProxyUndefined

When working with api's or objects, in some cases you may not know if a value exists in an object and it will result to doing something like

let requiredValue = SomeObject.name;

if(!requiredValue) { requiredValue = "Guest" }

// Or

if(!SomeObject.hasOwnProperty('name')) { requiredValue = "Guest" }

With ProxyUndefined using Javascript Proxy Function, all undefined paths will be replaced with the value you set as default.

const {optional, optionalFn} = require('proxy-undefined');

let requiredValue = optional(SomeObject, 'default value').name;

Example

const {optional} = require('proxy-undefined');

const data = {
    message: "Hello World",

    foo: () => {
        console.log('Foo function was called');
    },

    bar: () => {
        console.log('Bar function was called');
    }
};

console.log(data.message);;
// => Hello World

data.foo();
// => Foo function was called

//////////////////////////
// Using data.name (undefined)
console.log(data.name);
// => undefined

console.log(optional(data).name);
// => undefined

console.log(optional(data, 'John Doe').name);
// => John Doe


//////////////////////////
// Using  data.message (defined)
console.log(optional(data).message);
// => Hello World

console.log(optional(data, 'John Doe').message);
// => Hello World

Function Example

In Javascript if you call data.getFullName() and getFullName does not exists on the object we get an error.

with optionalFn you can set a default function if the one being called does not exists.

// Using same data above.
data.bar();
// => Bar function was called

data.getFullName();
// => THIS WILL CAUSE AN ERROR
// Error: data.getFullName is not a function

// Using `optionalFn`
optionalFn(data).getFullName();
// => undefined
// No Fatal Errors.

optionalFn(data, () => console.log('John P. Doe')).getFullName();
// => John P. Doe
// Default function ran instead.

console.log(optionalFn(data, 'john@doe.com').getEmail());
// => john@doe.com
// If default is not a function, it is returned directly.

Fn: exists/optional

Checks if path exists in object else returns [default=undefined]

const {exist} = require("proxy-undefined");

// is same as below, just an alias.


const {optional} = require("proxy-undefined");

Fn: fnExists/optionalFn

Checks if function exists else returns [default=() => undefined]

const {fnExist} = require("proxy-undefined");

// is same as below, just an alias.

const {optionalFn} = require("proxy-undefined");

Hope you find this Useful. :)