https://github.com/trapcodeio/proxy-undefined
Proxify javascript values to return a default value if undefined.
https://github.com/trapcodeio/proxy-undefined
Last synced: 3 months ago
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Proxify javascript values to return a default value if undefined.
- Host: GitHub
- URL: https://github.com/trapcodeio/proxy-undefined
- Owner: trapcodeio
- Created: 2019-06-14T14:12:34.000Z (about 6 years ago)
- Default Branch: master
- Last Pushed: 2019-06-15T21:49:46.000Z (about 6 years ago)
- Last Synced: 2025-03-11T01:47:25.148Z (4 months ago)
- Language: JavaScript
- Size: 6.84 KB
- Stars: 2
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: readme.md
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README
## ProxyUndefined
Return default value for object properties that does not exists i.e is **undefined**.
### Install
```console
npm install proxy-undefined
yarn add proxy-undefined
```
### Usage
```javascript
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
```javascript
let requiredValue = SomeObject.name;
if(!requiredValue) { requiredValue = "Guest" }
// Or
if(!SomeObject.hasOwnProperty('name')) { requiredValue = "Guest" }
```
With **ProxyUndefined** using [Javascript Proxy Function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy),
all undefined paths will be replaced with the value you set as default.
```javascript
const {optional, optionalFn} = require('proxy-undefined');
let requiredValue = optional(SomeObject, 'default value').name;
```
### Example
```javascript
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.
```javascript
// 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, '[email protected]').getEmail());
// => [email protected]
// If default is not a function, it is returned directly.
```
#### Fn: exists/optional
Checks if path exists in object else returns `[default=undefined]`
```javascript
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]`
```javascript
const {fnExist} = require("proxy-undefined");
// is same as below, just an alias.
const {optionalFn} = require("proxy-undefined");
```
Hope you find this Useful. :)