CoffeeScript: Difference between revisions

Revision as of 15:51, 30 July 2024

Revision as of 01:54, 4 August 2024

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<syntaxhighlight lang="javascript">

let mass = 72;

let height = 1.78;

let BMI = mass / height**2;

if (18.5 <= BMI && BMI < 25) alert('You are healthy!');

</syntaxhighlight>

Line 53:

To compute the [[greatest common divisor]] of two integers with the [[Euclidean algorithm]], in JavaScript one usually needs a ''while'' loop:

<syntaxhighlight lang="javascript">let gcd = (x, y) => {

gcd = (x, y) => {

do {

[x, y] = [y, x%y];

} while (y !== 0)

return x;

}</syntaxhighlight>

}

</syntaxhighlight>

Whereas in CoffeeScript one can use <code>until</code><ref>CoffeeScript calls this "[[pattern matching]]", which is a non-standard use of that term.</ref> instead:

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This would alert "No person" if the variable is <code>null</code> or <code>undefined</code> and "Have person" if there is something there.

A common pre-es6[[ES6]] JavaScript snippet using the [[jQuery]] library is:

<syntaxhighlight lang="javascript">

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The <code>for ... in</code> syntax allows looping over arrays while the <code>for ... of</code> syntax allows looping over objects.

CoffeeScript has been criticized for its unusual [[Scope (computer science)|scoping]] rules.<ref>{{cite web

rules.<ref>{{cite web

|url=http://lucumr.pocoo.org/2011/12/22/implicit-scoping-in-coffeescript/

|title=The Problem with Implicit Scoping in CoffeeScript

Line 152 ⟶ 149:

|date=25 July 2013

|access-date=2018-10-13

}}</ref> In particular, it completely disallows [[variable shadowing]] which makes reasoning about code more difficult and error-prone in some basic programming patterns established

by and taken for granted since [[procedural programming]] principles were defined.

error-prone in some basic programming patterns established

by and taken for granted since [[procedural programming]]

principles were defined.

For example, with the following code snippet in JavaScript

Line 172 ⟶ 167:

</syntaxhighlight>

In CoffeeScript there is no way to tell if the scope of a variable is limited to a block or not without looking outside the block.

is limited to a block or not without looking outside the block.

== Development and distribution ==