Introduction to Lazy Cache

Lazy caching is a powerful technique to optimize the performance and efficiency of your JavaScript applications by storing the results of expensive function calls and reusing them when the same inputs occur again. The lazy-cache package provides an easy and effective way to implement this pattern.

Getting Started

First, install lazy-cache via npm:

  npm install lazy-cache

API Examples

Basic Usage

The most basic use of lazy-cache allows you to cache values by their key:

  const lazy = require('lazy-cache')(require);
  const _ = lazy('lodash');
  
  lazy('config', () => require('./config.json'));

Caching Functions

You can also cache the results of function calls:

  lazy('expensiveCalculation', () => {
    return (arg1, arg2) => {
      // perform some expensive calculations here
      return arg1 + arg2;
    };
  });
  
  const result = lazy().expensiveCalculation(5, 7);

Lazy Load Dependencies

Lazy-cache can handle multiple dependencies:

  const { readFile } = lazy('fs').promises;
  const path = lazy('path');
  
  async function readConfig(configPath) {
    const fullPath = path().resolve(__dirname, configPath);
    const data = await readFile(fullPath, 'utf8');
    return JSON.parse(data);
  }

Real-world Application Example

This example demonstrates how you might use lazy-cache in a web server scenario using Express.js:

  const express = require('express');
  const lazy = require('lazy-cache')(require);
  
  lazy('database', () => require('./database'));
  lazy('config', () => require('./config'));
  
  const app = express();
  const db = lazy().database;
  
  app.get('/users', async (req, res) => {
    const users = await db.getUsers();
    res.json(users);
  });
  
  app.listen(lazy().config.port, () => {
    console.log(\`Server running on port \${lazy().config.port}\`);
  });

By lazy loading your dependencies, the application remains efficient and only loads the components when they are truly needed.

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