diff --git a/docs/index.html b/docs/index.html index 0d7c5869a..b0df6bd91 100644 --- a/docs/index.html +++ b/docs/index.html @@ -1,33 +1,30 @@ -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

3232
commits

20066
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:

on

Adds an event listener to an element with the ability to use event delegation.

Use EventTarget.addEventListener() to add an event listener to an element. If there is a target property supplied to the options object, ensure the event target matches the target specified and then invoke the callback by supplying the correct this context. Returns a reference to the custom delegator function, in order to be possible to use with off. Omit opts to default to non-delegation behavior and event bubbling.

const on = (el, evt, fn, opts = {}) => {
-  const delegatorFn = e => e.target.matches(opts.target) && fn.call(e.target, e);
-  el.addEventListener(evt, opts.target ? delegatorFn : fn, opts.options || false);
-  if (opts.target) return delegatorFn;
+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
3233
commits
20080
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:
 
converge
Accepts a converging function and a list of branching functions and returns a function that applies each branching function to the arguments and the results of the branching functions are passed as arguments to the converging function.
Use Array.map() and Function.apply() to apply each function to the given arguments. Use the spread operator (...) to call coverger with the results of all other functions.
const converge = (converger, fns) => (...args) => converger(...fns.map(fn => fn.apply(null, args)));
+
const average = converge((a, b) => a / b, [
+  arr => arr.reduce((a, v) => a + v, 0),
+  arr => arr.length
+]);
+average([1, 2, 3, 4, 5, 6, 7]); // 4
+
mapValues
Creates an object with the same keys as the provided object and values generated by running the provided function for each value.
Use Object.keys(obj) to iterate over the object's keys. Use Array.reduce() to create a new object with the same keys and mapped values using fn.
const mapValues = (obj, fn) =>
+  Object.keys(obj).reduce((acc, k) => {
+    acc[k] = fn(obj[k], k, obj);
+    return acc;
+  }, {});
+
const users = {
+  fred: { user: 'fred', age: 40 },
+  pebbles: { user: 'pebbles', age: 1 }
 };
-
const fn = () => console.log('!');
-on(document.body, 'click', fn); // logs '!' upon clicking the body
-on(document.body, 'click', fn, { target: 'p' }); // logs '!' upon clicking a `p` element child of the body
-on(document.body, 'click', fn, { options: true }); // use capturing instead of bubbling
-
randomHexColorCode
Generates a random hexadecimal color code.
Use Math.random to generate a random 24-bit(6x4bits) hexadecimal number. Use bit shifting and then convert it to an hexadecimal String using toString(16).
const randomHexColorCode = () => {
-  let n = (Math.random() * 0xfffff * 1000000).toString(16);
-  return '#' + n.slice(0, 6);
-};
-
randomHexColorCode(); // "#e34155"
-
unescapeHTML
Unescapes escaped HTML characters.
Use String.replace() with a regex that matches the characters that need to be unescaped, using a callback function to replace each escaped character instance with its associated unescaped character using a dictionary (object).
const unescapeHTML = str =>
-  str.replace(
-    /&|<|>|'|"/g,
-    tag =>
-      ({
-        '&': '&',
-        '&lt;': '<',
-        '&gt;': '>',
-        '&#39;': "'",
-        '&quot;': '"'
-      }[tag] || tag)
-  );
-
unescapeHTML('&lt;a href=&quot;#&quot;&gt;Me &amp; you&lt;/a&gt;'); // '<a href="#">Me & you</a>'
+mapValues(users, u => u.age); // { fred: 40, pebbles: 1 }
+
sumPower
Returns the sum of the powers of all the numbers from start to end (both inclusive).
Use Array.fill() to create an array of all the numbers in the target range, Array.map() and the exponent operator (**) to raise them to power and Array.reduce() to add them together. Omit the second argument, power, to use a default power of 2. Omit the third argument, start, to use a default starting value of 1.
const sumPower = (end, power = 2, start = 1) =>
+  Array(end + 1 - start)
+    .fill(0)
+    .map((x, i) => (i + start) ** power)
+    .reduce((a, b) => a + b, 0);
+
sumPower(10); // 385
+sumPower(10, 3); //3025
+sumPower(10, 3, 5); //2925
 

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.