ES8 Ecmascript 2017

JavaScript 2

Introduction

ECMAScript 2017, also known as ES8, introduced several important features that further enhanced JavaScript’s capabilities. Released in June 2017, it continued the trend of annual JavaScript updates, each bringing new features and improvements. ES8 focused on adding functionalities that simplified complex operations and improved asynchronous programming, making JavaScript more powerful and versatile for developers.

ECMAScript 2017 Language Specification

Detailed Feature Explanation with Examples

1. Async Functions (Async/Await)

Explanation:

  • Async functions, marked by the async keyword, enable writing asynchronous code in a more readable and linear style.
  • The await keyword is used inside async functions to pause execution until a promise is resolved.

Example:

javascript 
	async function fetchData() {
	  let data = await fetch('https://api.example.com');
	  return data.json();
	}

Pre-ES8 Comparison:

Before ES8, asynchronous code relied heavily on callbacks and promises, often leading to complex, nested code (callback hell).

2. Object.values and Object.entries

Explanation:

  • Object.values returns an array of a given object’s own enumerable property values.
  • Object.entries returns an array of a given object’s own enumerable string-keyed property [key, value] pairs.

Example:

javascript 
	const obj = { a: 1, b: 2 };
	console.log(Object.values(obj)); // [1, 2]
	console.log(Object.entries(obj)); // [['a', 1], ['b', 2]]

3. String Padding

Explanation:

  • String.prototype.padStart and String.prototype.padEnd allow padding the current string from the start or end with a specified string.

Example:

javascript 
	let str = 'ES8';
	console.log(str.padStart(4, '0')); // '0ES8'
	console.log(str.padEnd(4, '!')); // 'ES8!'

4. Object.getOwnPropertyDescriptors

Explanation:

  • Returns all own property descriptors of a given object.
  • Useful for object cloning or redefining properties.

Example:

javascript 
	const obj = { a: 1 };
	let descriptors = Object.getOwnPropertyDescriptors(obj);
	console.log(descriptors);

5. Trailing Commas in Function Parameter Lists and Calls

Explanation:

  • Allows trailing commas in function parameters, enhancing readability, especially in version control systems.

Example:

javascript 
	function example(a, b) {
	  // function logic
	}

Common Pitfalls

  • Misusing async/await leading to unhandled promises.
  • Overlooking the benefits of Object.entries and Object.values for object manipulation.

Further Reading

Summary

ES8 brought significant advancements to JavaScript, particularly in simplifying asynchronous programming with async/await. It also introduced utility functions for objects and strings that enhance the language’s flexibility and ease of use. These features, though seem small, have a substantial impact on writing cleaner, more efficient, and maintainable JavaScript code, highlighting the ongoing evolution of the language to meet the needs of modern web development.