diff --git a/docs/index.html b/docs/index.html index 74ec6eee5..3e95793f6 100644 --- a/docs/index.html +++ b/docs/index.html @@ -1,39 +1,25 @@ -30 seconds of code

logo 30 seconds of code

Curated collection of useful JavaScript snippets
that you can understand in 30 seconds or less.

305
snippets

119
contributors

3276
commits

20482
stars

Our philosophy

The core goal of 30 seconds of code is to provide a quality resource for beginner and advanced JavaScript developers alike. We want to help improve the JavaScript ecosystem, by lowering the barrier of entry for newcomers and help seasoned veterans pick up new tricks and remember old ones. In order to achieve this, we have collected hundreds of snippets that can be of use in a wide range of situations. We welcome new contributors and we like fresh ideas, as long as the code is short and easy to grasp in about 30 seconds. The only catch, if you may, is that many of our snippets are not perfectly suited for large, enterprise applications and they might not be deemed production-ready.


In order for 30 seconds of code to be as accessible and useful as possible, all of the snippets in the collection are licensed under the CC0-1.0 License, meaning they are absolutely free to use in any project you like. If you like what we do, you can always credit us, but that is not mandatory.


Today's picks

Our sophisticated robot helpers pick new snippets from our collection daily, so that you can discover new snippets to enhance your projects:

invertKeyValues

Inverts the key-value pairs of an object, without mutating it. The corresponding inverted value of each inverted key is an array of keys responsible for generating the inverted value. If a function is supplied, it is applied to each inverted key.

Use Object.keys() and Array.reduce() to invert the key-value pairs of an object and apply the function provided (if any). Omit the second argument, fn, to get the inverted keys without applying a function to them.

const invertKeyValues = (obj, fn) =>
-  Object.keys(obj).reduce((acc, key) => {
-    const val = fn ? fn(obj[key]) : obj[key];
-    acc[val] = acc[val] || [];
-    acc[val].push(key);
-    return acc;
-  }, {});
-
invertKeyValues({ a: 1, b: 2, c: 1 }); // { 1: [ 'a', 'c' ], 2: [ 'b' ] }
-invertKeyValues({ a: 1, b: 2, c: 1 }, value => 'group' + value); // { group1: [ 'a', 'c' ], group2: [ 'b' ] }
-

toCamelCase

Converts a string to camelcase.

Break the string into words and combine them capitalizing the first letter of each word, using a regexp.

const toCamelCase = str => {
-  let s =
-    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.slice(0, 1).toUpperCase() + x.slice(1).toLowerCase())
-      .join('');
-  return s.slice(0, 1).toLowerCase() + s.slice(1);
+30 seconds of code
logo 30 seconds of code
Curated collection of useful JavaScript snippets
that you can understand in 30 seconds or less.
305
snippets
119
contributors
3277
commits
20498
stars
Our philosophy
The core goal of 30 seconds of code is to provide a quality resource for beginner and advanced JavaScript developers alike. We want to help improve the JavaScript ecosystem, by lowering the barrier of entry for newcomers and help seasoned veterans pick up new tricks and remember old ones. In order to achieve this, we have collected hundreds of snippets that can be of use in a wide range of situations. We welcome new contributors and we like fresh ideas, as long as the code is short and easy to grasp in about 30 seconds. The only catch, if you may, is that many of our snippets are not perfectly suited for large, enterprise applications and they might not be deemed production-ready.

In order for 30 seconds of code to be as accessible and useful as possible, all of the snippets in the collection are licensed under the CC0-1.0 License, meaning they are absolutely free to use in any project you like. If you like what we do, you can always credit us, but that is not mandatory.

Today's picks
Our sophisticated robot helpers pick new snippets from our collection daily, so that you can discover new snippets to enhance your projects:
 
attempt
Attempts to invoke a function with the provided arguments, returning either the result or the caught error object.
Use a try... catch block to return either the result of the function or an appropriate error.
const attempt = (fn, ...args) => {
+  try {
+    return fn(...args);
+  } catch (e) {
+    return e instanceof Error ? e : new Error(e);
+  }
 };
-
toCamelCase('some_database_field_name'); // 'someDatabaseFieldName'
-toCamelCase('Some label that needs to be camelized'); // 'someLabelThatNeedsToBeCamelized'
-toCamelCase('some-javascript-property'); // 'someJavascriptProperty'
-toCamelCase('some-mixed_string with spaces_underscores-and-hyphens'); // 'someMixedStringWithSpacesUnderscoresAndHyphens'
-
toSnakeCase
Converts a string to snake case.
Break the string into words and combine them adding _ as a separator, using a regexp.
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-mixed_string With spaces_underscores-and-hyphens'); // 'some_mixed_string_with_spaces_underscores_and_hyphens'
-toSnakeCase('AllThe-small Things'); // "all_the_smal_things"
-toSnakeCase('IAmListeningToFMWhileLoadingDifferentURLOnMyBrowserAndAlsoEditingSomeXMLAndHTML'); // "i_am_listening_to_fm_while_loading_different_url_on_my_browser_and_also_editing_some_xml_and_html"
+
var elements = attempt(function(selector) {
+  return document.querySelectorAll(selector);
+}, '>_>');
+if (elements instanceof Error) elements = []; // elements = []
+
head
Returns the head of a list.
Use arr[0] to return the first element of the passed array.
const head = arr => arr[0];
+
head([1, 2, 3]); // 1
+
initializeNDArray
Create a n-dimensional array with given value.
Use recursion. Use Array.map() to generate rows where each is a new array initialized using initializeNDArray.
const initializeNDArray = (val, ...args) =>
+  args.length === 0
+    ? val
+    : Array.from({ length: args[0] }).map(() => initializeNDArray(val, ...args.slice(1)));
+
initializeNDArray(1, 3); // [1,1,1]
+initializeNDArray(5, 2, 2, 2); // [[[5,5],[5,5]],[[5,5],[5,5]]]
 

Getting started

Related projects
The idea behind 30 seconds of code has inspired some people to create similar collections in other programming languages and environments. Here are the ones we like the most:

Top contributors
chalarangelo Angelos Chalaris
fejes713 Stefan Feješ
flxwu Felix Wu
atomiks atomiks
kingdavidmartins King David Martins
kriadmin Rohit Tanwar
iamsoorena Soorena Soleimani
skatcat31 Robert Mennell
How to contribute
Do you have a cool idea for a new snippet? Maybe some code you use often and is not part of our collection? Contributing to 30 seconds of code is as simple as 1,2,3,4!
1
Create
Start by creating a snippet, according to the snippet template. Make sure to follow these simple guidelines:
  • Your snippet title must be unique and the same as the name of the implemented function.
  • Use the snippet description to explain what your snippet does and how it works.
  • Try to keep the snippet's code short and to the point. Use modern techniques and features.
  • Remember to provide an example of how your snippet works.
  • Your snippet should solve a real-world problem, no matter how simple.
  • Never modify README.md or any of the HTML files.
2
Tag
Run npm run tagger from your terminal, then open the tag_database file and tag your snippet appropriately. Multitagging is also supported, just make sure the first tag you specify is on of the major tags and the one that is most relevant to the implemneted function.
3
Test
You can optionally test your snippet to make our job easier. Simply run npm run tester to generate the test files for your snippet. Find the related folder for you snippet under the test directory and write some tests. Remember to run npm run tester again to make sure your tests are passing.
4
Pull request
If you have done everything mentioned above, you should now have an awesome snippet to add to our collection. Simply start a pull request and follow the guidelines provided. Remember to only submit one snippet per pull request, so that we can quickly evaluate and merge your code into the collection.
If you need additional pointers about writing a snippet, be sure to read the complete contribution guidelines.