Intro
JavaScript remains the most popular programming language in the world due to various reasons, and it is a general-purpose programming language that is standardized by ECMA-262 - ECMA International language specification. ECMAScript is the official name for JavaScript but JavaScript is the most recognized name around the world.
There are multiple editions introduced by ECMA-262 language specification throughout the time but ES5 (ECMAScript 2009) and ES6 (ECMAScript 2015) editions were significant.
Let’s explore ES5, ES6 differences together.
Differences
| ES5 | ES6 |
|---|---|
| 5th edition of the ECMA-262 language specification. | 6th edition of the ECMA-262 language specification. |
| Introduced in the year 2009. | Introduced in the year 2015. |
| There can be seen five primitive data types. string, number, boolean, null, undefined | Introduced a new primitive data type along with the data types that were there in ES5. string, number, boolean, null, undefined and symbol (Every symbol value returned from Symbol() is unique.) |
| ‘var’ keyword is the only keyword that was there to define the variables. | Introduced let and const keywords other than the ‘var’ keyword to define variables. |
| When comparing to ES6 performance is slightly low. | When comparing to ES5 performance is better. |
| Since var is used to define variables; there were slight disadvantages, type safety issues. There is a loose nature when comparing to ES6. Variable declared by var, have their scope globally. | Variable declared by let, have their scope in the block which they are declared, as well as in any contained sub-blocks. |
| Developers could not easily declare a constant variable which can not be redeclared when compared to ES6. | Constants(const) are block-scoped, much like variables declared using the let keyword. The value of a constant can't be changed through reassignment, and it can't be redeclared. Constants can be declared easily when compared to ES5. |
| function and return keywords are used to define a function. | ES6 introduces us to many great features like arrow functions, template strings, class destruction, Modules |
| Provide larger range of community support for ES5 when compared with ES6 | It provides a less range of community supports than that of ES5. |
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