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tessl/npm-utils-merge

Lightweight utility function for merging JavaScript objects with shallow property copying

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index.mddocs/

Utils Merge

Utils Merge is a lightweight utility library that provides a simple merge() function for merging JavaScript objects. The function copies all enumerable properties from a source object into a destination object, modifying the destination object in place with shallow copying behavior.

Package Information

  • Package Name: utils-merge
  • Package Type: npm
  • Language: JavaScript
  • Installation: npm install utils-merge

Core Imports

const merge = require('utils-merge');

For ES modules:

import merge from 'utils-merge';

Basic Usage

const merge = require('utils-merge');

// Basic object merging
const a = { foo: 'bar' };
const b = { bar: 'baz' };

merge(a, b);
console.log(a); // { foo: 'bar', bar: 'baz' }

// Property overwriting
const config = { host: 'localhost', port: 3000 };
const userConfig = { port: 8080, ssl: true };

merge(config, userConfig);
console.log(config); // { host: 'localhost', port: 8080, ssl: true }

Capabilities

Object Merging

Merges properties from a source object into a destination object with shallow copying.

/**
 * Merge object b with object a.
 * Copies all enumerable properties from source object into destination object.
 * Modifies the destination object in place and returns it.
 * 
 * @param {Object|null|undefined} a - Destination object that will be modified
 * @param {Object|null|undefined} b - Source object whose properties will be copied
 * @return {Object|null|undefined} - Returns the modified destination object (or a if null/undefined)
 */
function merge(a, b);

Behavior:

  • Performs shallow merge - only copies property values, not nested objects
  • Modifies the destination object a in place
  • Properties in source object b overwrite existing properties in destination object a
  • Returns the modified destination object a
  • If source object b is undefined or null, destination object a is returned unchanged
  • If destination object a is undefined or null, it is returned as-is
  • Function safely handles null/undefined inputs without throwing errors

Usage Examples:

const merge = require('utils-merge');

// Simple merging
const target = { name: 'Alice' };
const source = { age: 25, city: 'Boston' };
const result = merge(target, source);
// target is now { name: 'Alice', age: 25, city: 'Boston' }
// result === target (same reference)

// Property overwriting
const defaults = { timeout: 5000, retries: 3 };
const options = { timeout: 10000 };
merge(defaults, options);
// defaults is now { timeout: 10000, retries: 3 }

// Handling undefined source
const obj = { foo: 'bar' };
merge(obj, undefined);
// obj remains { foo: 'bar' }

// Configuration merging pattern
function createClient(userOptions = {}) {
  const defaultOptions = {
    host: 'api.example.com',
    port: 443,
    timeout: 5000,
    retries: 3
  };
  
  return merge(defaultOptions, userOptions);
}

const client = createClient({ port: 8080, ssl: false });
// Returns: { host: 'api.example.com', port: 8080, timeout: 5000, retries: 3, ssl: false }

docs

index.md

tile.json