diff --git a/docs/index.html b/docs/index.html index 8a19919cd..63d8fdb8f 100644 --- a/docs/index.html +++ b/docs/index.html @@ -1,27 +1,22 @@ -30 seconds of code

logo 30 seconds of code

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

313
snippets

120
contributors

3365
commits

20968
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 a few of our snippets are not perfectly optimized 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:

functions

Returns an array of function property names from own (and optionally inherited) enumerable properties of an object.

Use Object.keys(obj) to iterate over the object's own properties. If inherited is true, use Object.get.PrototypeOf(obj) to also get the object's inherited properties. Use Array.filter() to keep only those properties that are functions. Omit the second argument, inherited, to not include inherited properties by default.

const functions = (obj, inherited = false) =>
-  (inherited
-    ? [...Object.keys(obj), ...Object.keys(Object.getPrototypeOf(obj))]
-    : Object.keys(obj)
-  ).filter(key => typeof obj[key] === 'function');
-
function Foo() {
-  this.a = () => 1;
-  this.b = () => 2;
-}
-Foo.prototype.c = () => 3;
-functions(new Foo()); // ['a', 'b']
-functions(new Foo(), true); // ['a', 'b', 'c']
-

isNull

Returns true if the specified value is null, false otherwise.

Use the strict equality operator to check if the value and of val are equal to null.

const isNull = val => val === null;
-
isNull(null); // true
-

sortedIndexBy

Returns the lowest index at which value should be inserted into array in order to maintain its sort order, based on a provided iterator function.

Check if the array is sorted in descending order (loosely). Use Array.findIndex() to find the appropriate index where the element should be inserted, based on the iterator function fn.

const sortedIndexBy = (arr, n, fn) => {
-  const isDescending = fn(arr[0]) > fn(arr[arr.length - 1]);
-  const val = fn(n);
-  const index = arr.findIndex(el => (isDescending ? val >= fn(el) : val <= fn(el)));
-  return index === -1 ? arr.length : index;
+30 seconds of code
logo 30 seconds of code
Curated collection of useful JavaScript snippets
that you can understand in 30 seconds or less.
313
snippets
120
contributors
3366
commits
20979
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 a few of our snippets are not perfectly optimized 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:
 
promisify
Converts an asynchronous function to return a promise.
Use currying to return a function returning a Promise that calls the original function. Use the ...rest operator to pass in all the parameters.
In Node 8+, you can use util.promisify
const promisify = func => (...args) =>
+  new Promise((resolve, reject) =>
+    func(...args, (err, result) => (err ? reject(err) : resolve(result)))
+  );
+
const delay = promisify((d, cb) => setTimeout(cb, d));
+delay(2000).then(() => console.log('Hi!')); // // Promise resolves after 2s
+
show
Shows all the elements specified.
Use the spread operator (...) and Array.forEach() to clear the display property for each element specified.
const show = (...el) => [...el].forEach(e => (e.style.display = ''));
+
show(...document.querySelectorAll('img')); // Shows all <img> elements on the page
+
uncurry
Uncurries a function up to depth n.
Return a variadic function. Use Array.reduce() on the provided arguments to call each subsequent curry level of the function. If the length of the provided arguments is less than n throw an error. Otherwise, call fn with the proper amount of arguments, using Array.slice(0, n). Omit the second argument, n, to uncurry up to depth 1.
const uncurry = (fn, n = 1) => (...args) => {
+  const next = acc => args => args.reduce((x, y) => x(y), acc);
+  if (n > args.length) throw new RangeError('Arguments too few!');
+  return next(fn)(args.slice(0, n));
 };
-
sortedIndexBy([{ x: 4 }, { x: 5 }], { x: 4 }, o => o.x); // 0
+
const add = x => y => z => x + y + z;
+const uncurriedAdd = uncurry(add, 3);
+uncurriedAdd(1, 2, 3); // 6
 

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.