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### Enhancing Node.js Skills
## JavaScript Object Methods
---
## Introduction to Object Methods
- Essential part of JavaScript programming.
- Used extensively in Node.js and web development.
- Enhance code readability and efficiency.
---
## What are Object Methods?
- Functions associated with an object.
- Allow you to manipulate, access, and manage data within objects.
- Examples: `Object.keys()`, `Object.values()`, `Object.entries()`
---
## Why are They Important?
* **Enhanced Code Structure and Readability:**
Object methods encourage a more structured approach to coding. By encapsulating functionality within objects, code becomes easier to read and understand.
---
* **Improved Data Handling and Manipulation:**
JavaScript objects are often used to represent data models. Object methods provide efficient ways to manipulate this data, such as adding, modifying, or deleting properties.
---
* **Encouragement of the DRY Principle (Don't Repeat Yourself):**
Object methods can be reused across different parts of an application. This avoids the need for repetitive code.
---
* **Performance Optimization:**
Efficient use of object methods can significantly impact the performance of a web application.
---
## Today's Focus
- Introduce a few key object methods.
- Understand their usage with simple examples.
- Learn best practices in a Node.js context.
---
## Method 1: `Object.keys()`
- Retrieves all the keys from a JavaScript object.
- Returns an array of strings representing the property names.
**Example Code:**
```javascript
const person = { name: 'Alice', age: 25, job: 'Engineer' };
const keys = Object.keys(person);
console.log(keys);
```
---
```text
['name', 'age', 'job']
```
---
## `Object.keys()`
#### Scenario: Filtering User Data
Imagine you have an object representing user data, and you need to create a list of all the fields (keys) that have non-empty values. This scenario is common in form data processing or data validation.
---
```javascript
const userData = {
name: "John Doe",
email: "johndoe@example.com",
age: 30,
address: "",
phoneNumber: "123-456-7890"
};
```
#### Filtering non-empty fields:
```javascript
const nonEmptyFields =
Object.keys(userData)
.filter(key => userData[key] !== "");
console.log(nonEmptyFields);
```
---
```text
['name', 'email', 'age', 'phoneNumber']
```
---
## Method 2: `Object.values()`
- Complements `Object.keys()` by retrieving all the values.
- Returns an array containing the values of each property in the object.
**Example Code:**
```javascript
const person = {
name: 'Alice',
age: 25,
job: 'Engineer'
};
const values = Object.values(person);
console.log(values);
```
---
```text
['Alice', 25, 'Engineer']
```
---
## Method 3: `Object.entries()`
- Returns an array of key-value pairs.
- Useful for iterating over objects.
**Example Code:**
```javascript
const person = {
name: 'Alice',
age: 25,
job: 'Engineer'
};
const entries = Object.entries(person);
console.log(entries);
```
---
```text
[['name', 'Alice'], ['age', 25], ['job', 'Engineer']]
```
---
## Method 4: `Object.assign()`
- Used to copy values from one or more source objects to a target object.
- Demonstrates shallow copying.
---
**Example Code:**
```javascript
const person = {
name: 'Alice',
age: 25,
job: 'Engineer'
};
const contactDetails = {
email: 'alice@example.com',
phone: '123-456-7890'
};
const combinedDetails = Object.assign({}, person, contactDetails);
console.log(combinedDetails);
```
---
```text
{
name: 'Alice',
age: 25,
job: 'Engineer',
email: 'alice@example.com',
phone: '123-456-7890'
}
```
---
## Method 5: `Object.freeze()`
- Makes an object immutable, preventing new properties from being added.
- Existing properties cannot be removed or altered.
**Example Code:**
```javascript
const frozenPerson = Object.freeze(person);
frozenPerson.age = 30;
console.log(frozenPerson);
```
---
```text
{ name: 'Alice', age: 25, job: 'Engineer' }
```
---
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