17 March 2025
ES6 (ECMAScript 2015) marked a pivotal moment in JavaScript's evolution. It wasn't just an update; it was a transformation. ES6 introduced a suite of powerful new features and syntax enhancements that fundamentally changed how developers write JavaScript, paving the way for more robust, maintainable, and efficient applications. This release addressed many of the language's long-standing limitations and brought it closer to the capabilities of other modern programming languages. Among the many significant advancements were:
Syntax Changes
Modules and Classes
Symbols
Iterators & Generators
Promises
Built-in Object Extensions
Maps & Sets
The Reflect API
The Proxy API
Despite newer ECMAscript versions, ES6 remains crucial because it introduced the fundamental features that are now ubiquitous in modern JavaScript development.
let
Scope: let provides block scoping, ensuring variables are confined to the scope in which they are defined
Re-assignability: Variables declared with let can be reassigned
Hoisting: Unlike var, let variables are not hoisted to the top of their scope. If a let variable is used before its declaration, it results in an error, or in older engines an undefined value.
const
Cannot be re-assign. Defined only once
Points to stored space memory hence assigned arrays/objects (reference type) can be manipulated
Hoisting: Similar to let, const variables are not hoisted. They must be declared before use.
Arrow functions offer a more concise syntax compared to traditional function declarations
The this keyword works differently in Arrow Functions. Arrow functions lexically bind this, meaning they inherit the this value from surrounding scope. In contrast, traditional functions require methods like .bind(), .apply(), or .call() to manage this context.
ES6 introduced default values for functions parameters. Before ES6, default values were often handled by checking if a parameter was undefined within the function body. A parameter can have a default value that depends on the previous parameter.
ES6 allows the use of variable names as object keys, with the variable's value automatically assigned to the key
The REST operator in ES6 serves to gather any number of passed arguments into a single array, effectively bundling them for further use within a function.
Almost the same with Rest Operator but the other way around. Splitting up an array into a list of values.
The for...of loop is specifically designed for iterating over iterable objects, such as arrays. It differs from the other loop methods in its ability to directly access the values of iterable objects.
This also works with Set object.
Template literals are strings enclosed in backticks (` `) that support string interpolation and multiline strings.
You can also perform expressions inside it.
To handle a multiline string, see the example below:
It can also be used like this:
Destructuring allows you to extract values from arrays into distinct variables
Stay tuned for Part 2, where we will explore more features introduced in ES6.
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