Javascript Destructuring - Extraction (The Fun Way🧑🏽‍💻)
Tags: javascript, webdev, node
Published: 2020-05-16 15:13:44

Struggle of every developer is to minimize the boilerplate and maximize the efficiency. This is where the Destructuring pitches in for JavaScript, to make it more understandable, simple and a clean one.

## Object Destructuring
```javascript
   const { propertyName1, propertyName2 } = objectName;
```
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As mentioned above example, the 3 lines used for extracting 3 properties (`name, age & gender`) from the `person` object, is reduced to a single line using shorthand destructuring. If we need to extract *N* properties to variables, we would need *N* statements, but we could do that in 1 statement using destructuring.
<br /><br />
## Array Destructuring
```javascript
   // Convention Using Index
   const element1 = array[0];
   const element2 = array[1];
   // Destructuring
   const [ element1, element2, ...remaining ] = array;
```
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Conventionally elements of the array are extracted using the index of the element, but using ES6 destructuring we can get the values of the mentioned indexes in a single statement. Also by using the `...` - spread operator, we could collect the remaining elements as array into a single variable.
<br /><br />
## Aliases
```javascript
   // Alias name
   const { propertyName: aliasName } = objectName;
```
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Aliases helps in extracting similar properties from different objects. This finds many real-time application in modern programming.
<br /><br />
## Defaults
```javascript
   // Default values - Object
   const { propertyName = defaultValue } = objectName;
   // Default values - Array
   const [ element1 = value1, element2 = value2 ] = array;
```
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Sometimes, we might not be sure if the property is present in the required object or an element in a particular index position, but those values returning as `undefined` would break the application. This is where the `default` values come in.
<br /><br />
## Functional Param - Destructuring
The above mentioned concepts can be used for the destructuring the incoming object or array in the method signatures. Hope the below snippet explains them.
```javascript
   const welcomeUser = ({ name: username = 'Anonymous', topics }) => {
      // Moved the below logic to the function signature.
      // const {name: username = 'Anonymous', topics} = user;
      console.log(`${username} has subscribed to the following topics - 
                   ${topics.join(', ')}`);
   }
   welcomeUser({
      name: 'John Doe',
      topics: ['nodejs', 'javascript', 'deno']
   });
   // John Doe has subscribed to the following topics - nodejs, javascript, deno

   welcomeUser({
      topics: ['react', 'javascript', 'angular']
   });
   // Anonymous has subscribed to the following topics - react, javascript, angular
```

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Thanks for reading this far. This is my first attempt in writing a technical blog, any feedback would be appreciated.