diff --git a/README.md b/README.md index 25eb329d1..5b770f8c1 100644 --- a/README.md +++ b/README.md @@ -795,12 +795,19 @@ const sample = arr => arr[Math.floor(Math.random() * arr.length)]; ### shuffle -Randomizes the order of the values of an array. +Randomizes the order of the values of an array, in place. -Use `Array.sort()` to reorder elements, using `Math.random()` in the comparator. +Uses the Fisher-Yates algoritm to reorder the elements of the array, based on the [Lodash implimentation](https://github.com/lodash/lodash/blob/b2ea6b1cd251796dcb5f9700c4911a7b6223920b/shuffle.js) ```js -const shuffle = arr => arr.sort(() => Math.random() - 0.5); +const shuffle = ([...arr]) => { + let m = arr.length; + while (m) { + const i = Math.floor(Math.random() * m--); + [arr[m], arr[i]] = [arr[i], arr[m]]; + } + return arr; +}; // shuffle([1,2,3]) -> [2,3,1] ``` @@ -2093,12 +2100,13 @@ const toSnakeCase = str =>{ str && str.match(/[A-Z]{2,}(?=[A-Z][a-z]+[0-9]*|\b)|[A-Z]?[a-z]+[0-9]*|[A-Z]|[0-9]+/g) .map(x => x.toLowerCase()) .join('_'); +} // toSnakeCase("camelCase") -> 'camel_case' // toSnakeCase("some text") -> 'some_text' // toSnakeCase("some-javascript-property") -> 'some_javascript_property' // toSnakeCase("some-mixed_string With spaces_underscores-and-hyphens") -> 'some_mixed_string_with_spaces_underscores_and_hyphens' -// toKebabCase("AllThe-small Things") -> "all_the_smal_things" -// toKebabCase('IAmListeningToFMWhileLoadingDifferentURLOnMyBrowserAndAlsoEditingSomeXMLAndHTML') -> "i_am_listening_to_fm_while_loading_different_url_on_my_browser_and_also_editing_some_xml_and_html" +// toSnakeCase("AllThe-small Things") -> "all_the_small_things" +// toSnakeCase('IAmListeningToFMWhileLoadingDifferentURLOnMyBrowserAndAlsoEditingSomeXMLAndHTML') -> "i_am_listening_to_fm_while_loading_different_url_on_my_browser_and_also_editing_some_xml_and_html" ``` [⬆ back to top](#table-of-contents) diff --git a/docs/index.html b/docs/index.html index 52920974d..aa9f6c31e 100644 --- a/docs/index.html +++ b/docs/index.html @@ -586,9 +586,16 @@ This method also works with strings.

// sample([3, 7, 9, 11]) -> 9

shuffle

-

Randomizes the order of the values of an array.

-

Use Array.sort() to reorder elements, using Math.random() in the comparator.

-
const shuffle = arr => arr.sort(() => Math.random() - 0.5);
+
Randomizes the order of the values of an array, in place.

+
Uses the Fisher-Yates algoritm to reorder the elements of the array, based on the Lodash implimentation

+
const shuffle = ([...arr]) => {
+  let m = arr.length;
+  while (m) {
+    const i = Math.floor(Math.random() * m--);
+    [arr[m], arr[i]] = [arr[i], arr[m]];
+  }
+  return arr;
+};
 // shuffle([1,2,3]) -> [2,3,1]

similarity

@@ -1326,12 +1333,13 @@ For more detailed explanation of this Regex,

truncateString

Truncates a string up to a specified length.

diff --git a/snippets/shuffle.md b/snippets/shuffle.md index 27d7fd783..54687f67f 100644 --- a/snippets/shuffle.md +++ b/snippets/shuffle.md @@ -1,10 +1,17 @@ ### shuffle -Randomizes the order of the values of an array. +Randomizes the order of the values of an array, in place. -Use `Array.sort()` to reorder elements, using `Math.random()` in the comparator. +Uses the Fisher-Yates algoritm to reorder the elements of the array, based on the [Lodash implimentation](https://github.com/lodash/lodash/blob/b2ea6b1cd251796dcb5f9700c4911a7b6223920b/shuffle.js) ```js -const shuffle = arr => arr.sort(() => Math.random() - 0.5); +const shuffle = ([...arr]) => { + let m = arr.length; + while (m) { + const i = Math.floor(Math.random() * m--); + [arr[m], arr[i]] = [arr[i], arr[m]]; + } + return arr; +}; // shuffle([1,2,3]) -> [2,3,1] ```