Introduction to Deep Extend

Deep Extend is a powerful library for merging JavaScript objects. It provides advanced features for deep merging nested objects, making it an essential tool for developers dealing with complex data structures. In this post, we will explore the various APIs offered by Deep Extend with code snippets for better understanding.

Basic Usage

To get started, you need to install the Deep Extend library:

npm install deep-extend

API: deepExtend

This is the primary function of the library, used for merging objects. Here’s how it works:

  const deepExtend = require('deep-extend');

  const obj1 = {
    name: 'Alice',
    info: { age: 25 }
  };

  const obj2 = {
    info: { gender: 'female' }
  };

  const result = deepExtend(obj1, obj2);
  console.log(result);
  // Output: { name: 'Alice', info: { age: 25, gender: 'female' } }

Merging Arrays

Deep Extend also supports merging arrays:

  const obj1 = {
    hobbies: ['reading']
  };

  const obj2 = {
    hobbies: ['sports']
  };

  const result = deepExtend(obj1, obj2);
  console.log(result);
  // Output: { hobbies: ['reading', 'sports'] }

Array and Object Combined

You can handle more complex structures involving both arrays and objects:

  const obj1 = {
    data: [{ name: 'Alice' }]
  };

  const obj2 = {
    data: [{ age: 25 }]
  };

  const result = deepExtend(obj1, obj2);
  console.log(result);
  // Output: { data: [{ name: 'Alice', age: 25 }] }

N-Level Deep Merge

Deep Extend supports n-level deep merging. Here’s an example:

  const obj1 = {
    level1: {
      level2: {
        level3: { name: 'Alice' }
      }
    }
  };

  const obj2 = {
    level1: {
      level2: {
        level3: { age: 25 }
      }
    }
  };

  const result = deepExtend(obj1, obj2);
  console.log(result);
  // Output: { level1: { level2: { level3: { name: 'Alice', age: 25 } } } }

Application Example

Let’s consider a simple application where we use Deep Extend to manage user profiles:

  const deepExtend = require('deep-extend');

  let defaultProfile = {
    preferences: {
      theme: 'light',
      notifications: true
    },
    data: {
      name: 'User'
    }
  };

  let userProfile = {
    preferences: {
      theme: 'dark'
    },
    data: {
      name: 'John Doe',
      age: 30
    }
  };

  const finalProfile = deepExtend(defaultProfile, userProfile);
  console.log(finalProfile);
  // Output: {
  //   preferences: { theme: 'dark', notifications: true },
  //   data: { name: 'John Doe', age: 30 }
  // }

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By mastering Deep Extend, you can efficiently handle complex JavaScript object merging scenarios, making your code more manageable and dynamic.

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