JavaScript Mastery

Currying, Throttle & Promises

Master three essential JavaScript patterns that elevate your code from functional to exceptional. Interactive examples included.

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01

Currying

Transform functions with multiple arguments into a sequence of functions, each taking a single argument. This functional programming technique enables partial application and code reusability.

Partial Application

Fix arguments progressively for reusable function variants

Function Composition

Build complex logic from simple, testable functions 

const multiply = (a) => (b) => (c) => a * b * c;

// Usage
const multiplyBy2 = multiply(2);
const multiplyBy2And3 = multiplyBy2(3);

multiplyBy2And3(4); // 24

Interactive Demo

Live Visualization

Throttle Limit: 1000ms
0
Normal Calls
0
Throttled Calls
// Click the button to see throttling in action...
02

Throttle

Limit the rate at which a function can fire. Essential for performance optimization in scroll handlers, resize events, and API calls to prevent overwhelming the browser or server.

Performance

Reduce unnecessary calculations during rapid events

Rate Limiting

Protect APIs from excessive client requests

function throttle(func, limit) {
  let inThrottle;
  return function(...args) {
    if (!inThrottle) {
      func.apply(this, args);
      inThrottle = true;
      setTimeout(() => inThrottle = false, limit);
    }
  }
}
03

Promises

Represent the eventual completion (or failure) of an asynchronous operation and its resulting value. The foundation of modern asynchronous JavaScript programming.

Pending Initial state
Fulfilled Operation completed
Rejected Operation failed 
const fetchData = () => {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      const success = Math.random() > 0.5;
      success ? resolve('Data loaded!') 
              : reject('Error!');
    }, 1000);
  });
};

Promise Simulator

Active Promises
Click buttons to create promises...
0 Pending
0 Fulfilled
0 Rejected

Real-World Integration

See how these concepts work together in a practical API request manager

api-manager.js 
const createAPIClient = (baseURL) => (authToken) => {
  // Curried configuration
  const headers = {
    'Authorization': `Bearer ${authToken}`,
    'Content-Type': 'application/json'
  };

  // Throttled request function
  const throttledFetch = throttle(async (endpoint) => {
    const response = await fetch(`${baseURL}${endpoint}`, { headers });
    return response.json();
  }, 1000);

  return (endpoint) => new Promise((resolve) => {
    throttledFetch(endpoint).then(resolve);
  });
};

// Usage
const api = createAPIClient('https://api.example.com')('token123');