diff --git a/docs/index.html b/docs/index.html index f4b2cb91f..bec81cc50 100644 --- a/docs/index.html +++ b/docs/index.html @@ -1,48 +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.

304
snippets

118
contributors

3234
commits

20088
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:

maxN

Returns the n maximum elements from the provided array. If n is greater than or equal to the provided array's length, then return the original array(sorted in descending order).

Use Array.sort() combined with the spread operator (...) to create a shallow clone of the array and sort it in descending order. Use Array.slice() to get the specified number of elements. Omit the second argument, n, to get a one-element array.

const maxN = (arr, n = 1) => [...arr].sort((a, b) => b - a).slice(0, n);
-
maxN([1, 2, 3]); // [3]
-maxN([1, 2, 3], 2); // [3,2]
-

rearg

Creates a function that invokes the provided function with its arguments arranged according to the specified indexes.

Use Array.reduce() and Array.indexOf() to reorder arguments based on indexes in combination with the spread operator (...) to pass the transformed arguments to fn.

const rearg = (fn, indexes) => (...args) =>
-  fn(
-    ...args.reduce(
-      (acc, val, i) => ((acc[indexes.indexOf(i)] = val), acc),
-      Array.from({ length: indexes.length })
-    )
-  );
-
var rearged = rearg(
-  function(a, b, c) {
-    return [a, b, c];
+30 seconds of code
logo 30 seconds of code
Curated collection of useful JavaScript snippets
that you can understand in 30 seconds or less.
304
snippets
118
contributors
3235
commits
20098
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:
 
isBrowserTabFocused
Returns true if the browser tab of the page is focused, false otherwise.
Use the Document.hidden property, introduced by the Page Visibility API to check if the browser tab of the page is visible or hidden.
const isBrowserTabFocused = () => !document.hidden;
+
isBrowserTabFocused(); // true
+
transform
Applies a function against an accumulator and each key in the object (from left to right).
Use Object.keys(obj) to iterate over each key in the object, Array.reduce() to call the apply the specified function against the given accumulator.
const transform = (obj, fn, acc) => Object.keys(obj).reduce((a, k) => fn(a, obj[k], k, obj), acc);
+
transform(
+  { a: 1, b: 2, c: 1 },
+  (r, v, k) => {
+    (r[v] || (r[v] = [])).push(k);
+    return r;
   },
-  [2, 0, 1]
-);
-rearged('b', 'c', 'a'); // ['a', 'b', 'c']
-
recordAnimationFrames
Invokes the provided callback on each animation frame.
Use recursion. Provided that running is true, continue invoking window.requestAnimationFrame() which invokes the provided callback. Return an object with two methods start and stop to allow manual control of the recording. Omit the second argument, autoStart, to implicitly call start when the function is invoked.
const recordAnimationFrames = (callback, autoStart = true) => {
-  let running = true,
-    raf;
-  const stop = () => {
-    running = false;
-    cancelAnimationFrame(raf);
-  };
-  const start = () => {
-    running = true;
-    run();
-  };
-  const run = () => {
-    raf = requestAnimationFrame(() => {
-      callback();
-      if (running) run();
-    });
-  };
-  if (autoStart) start();
-  return { start, stop };
-};
-
const cb = () => console.log('Animation frame fired');
-const recorder = recordAnimationFrames(cb); // logs 'Animation frame fired' on each animation frame
-recorder.stop(); // stops logging
-recorder.start(); // starts again
-const recorder2 = recordAnimationFrames(cb, false); // `start` needs to be explicitly called to begin recording frames
+  {}
+); // { '1': ['a', 'c'], '2': ['b'] }
+
UUIDGeneratorBrowser
Generates a UUID in a browser.
Use crypto API to generate a UUID, compliant with RFC4122 version 4.
const UUIDGeneratorBrowser = () =>
+  ([1e7] + -1e3 + -4e3 + -8e3 + -1e11).replace(/[018]/g, c =>
+    (c ^ (crypto.getRandomValues(new Uint8Array(1))[0] & (15 >> (c / 4)))).toString(16)
+  );
+
UUIDGeneratorBrowser(); // '7982fcfe-5721-4632-bede-6000885be57d'
 

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.