CoffeeScript: Difference between revisions

Revision as of 14:30, 14 October 2021

Revision as of 14:22, 5 November 2021

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</syntaxhighlight>

To compute the [[greatest common divisor]] of two integers with the [[euclidean algorithm]], in JavaScript one usually needs a ''while'' loop:{{Update inline|date=May 2021|reason=JavaScript also supports destructuring assignment}}

<syntaxhighlight lang="javascript">

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</syntaxhighlight>

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

<syntaxhighlight lang="coffeescript">

gcd = (x, y) ->

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x

</syntaxhighlight>

Any ''for'' loop can be replaced by a [[list comprehension]]; so that to compute the squares of the positive odd numbers smaller than ten (i.e. numbers whose remainder modulo 2 is 1), one can do:

<syntaxhighlight lang="coffeescript">

alert n*n for n in [1..10] when n%2 is 1

</syntaxhighlight>

Alternatively, there is:

<syntaxhighlight lang="coffeescript">

alert n*n for n in [1..10] by 2

</syntaxhighlight>

A [[linear search]] can be implemented with a one-liner using the when keyword:

<syntaxhighlight lang="coffeescript">

names = ["Ivan", "Joanna", "Nikolay", "Mihaela"]

linearSearch = (searchName) -> alert(name) for name in names when name is searchName

</syntaxhighlight>

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

The <code>?</code> keyword quickly checks if a variable is <code>null</code> or <code>undefined</code> :

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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 JavaScript snippet using the [[jQuery]] library is:

<syntaxhighlight lang="javascript">

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sentence = "#{ 22 / 7 } is a decent approximation of π"

</syntaxhighlight>

Any ''for'' loop can be replaced by a [[list comprehension]]; so that to compute the squares of the positive odd numbers smaller than ten (i.e. numbers whose remainder modulo 2 is 1), one can do:

<syntaxhighlight lang="coffeescript">

alert n*n for n in [1..10] when n%2 is 1

</syntaxhighlight>

Alternatively, there is:

<syntaxhighlight lang="coffeescript">

alert n*n for n in [1..10] by 2

</syntaxhighlight>

A [[linear search]] can be implemented with a one-liner using the when keyword:

<syntaxhighlight lang="coffeescript">

names = ["Ivan", "Joanna", "Nikolay", "Mihaela"]

linearSearch = (searchName) -> alert(name) for name in names when name is searchName

</syntaxhighlight>

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 scoping