diff --git a/1-js/05-data-types/05-array-methods/article.md b/1-js/05-data-types/05-array-methods/article.md index 5a1a7762..b420f33f 100644 --- a/1-js/05-data-types/05-array-methods/article.md +++ b/1-js/05-data-types/05-array-methods/article.md @@ -384,7 +384,7 @@ The order became `1, 15, 2`. Incorrect. But why? **The items are sorted as strings by default.** -Literally, all elements are converted to strings for comparisons. For strings, lexicographic ordering is applied and indeed `"2" > "15"`. +Literally, all elements are converted to strings for comparisons. For strings, lexicographic ordering is applied and indeed `"2" > "15"`. To use our own sorting order, we need to supply a function as the argument of `arr.sort()`. @@ -431,7 +431,6 @@ By the way, if we ever want to know which elements are compared -- nothing preve The algorithm may compare an element with multiple others in the process, but it tries to make as few comparisons as possible. - ````smart header="A comparison function may return any number" Actually, a comparison function is only required to return a positive number to say "greater" and a negative number to say "less". @@ -456,6 +455,22 @@ arr.sort( (a, b) => a - b ); This works exactly the same as the longer version above. ```` +````smart header="Use `localeCompare` for strings" +Remember [strings](info:string#correct-comparisons) comparison algorithm? It compares letters by their codes by default. + +For many alphabets, it's better to use `str.localeCompare` method to correctly sort letters, such as `Ö`. + +For example, let's sort a few countries in German: + +```js run +let countries = ['Österreich', 'Andorra', 'Vietnam']; + +alert( countries.sort( (a, b) => a > b ? 1 : -1) ); // Andorra, Vietnam, Österreich (wrong) + +alert( countries.sort( (a, b) => a.localeCompare(b) ) ); // Andorra,Österreich,Vietnam (correct!) +``` +```` + ### reverse The method [arr.reverse](mdn:js/Array/reverse) reverses the order of elements in `arr`.