What Does '=>' Mean in JavaScript Arrow Functions?

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What Does "=>" Mean in JavaScript?

The "=>" symbol, commonly known as the arrow function, is a concise syntax introduced in ECMAScript 6 for expressing function expressions. It offers several key advantages:

Arrow Function: A Lexical Nexus

Arrow functions inherit the this value from their surrounding scope, unlike traditional functions. This eliminates the need for complex constructs like self = this to preserve this across nested functions.

Concise Syntax

Arrow functions are notably more compact than function expressions. Consider the following example:

// Old-style function expression
var a2 = a.map(function(s) { return s.length; });

// Arrow function
var a3 = a.map(s => s.length);

Both a2 and a3 will result in the same output ([31, 30, 31, 31]), but the arrow function is significantly more concise.

Compatibility Notes

While arrow functions are supported in Node, browser support varies. As of December 12, 2017, they are supported in current versions of many popular browsers, including:

• Chrome (v. 45 )
• Firefox (v. 22 )
• Edge (v. 12 )
• Opera (v. 32 )

However, support for IE (through v. 11) and other lesser-known browsers is lacking. For the latest and most comprehensive compatibility information, refer to CanIUse.com.

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