diff --git a/docs/index.html b/docs/index.html index e07ae7c0a..928744719 100644 --- a/docs/index.html +++ b/docs/index.html @@ -1,18 +1,34 @@ -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

3223
commits

20010
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:

initialize2DArray

Initializes a 2D array of given width and height and value.

Use Array.map() to generate h rows where each is a new array of size w initialize with value. If the value is not provided, default to null.

const initialize2DArray = (w, h, val = null) =>
-  Array.from({ length: h }).map(() => Array.from({ length: w }).fill(val));
-
initialize2DArray(2, 2, 0); // [[0,0], [0,0]]
-

initializeArrayWithRange

Initializes an array containing the numbers in the specified range where start and end are inclusive with their common difference step.

Use Array.from(Math.ceil((end+1-start)/step)) to create an array of the desired length(the amounts of elements is equal to (end-start)/step or (end+1-start)/step for inclusive end), Array.map() to fill with the desired values in a range. You can omit start to use a default value of 0. You can omit step to use a default value of 1.

const initializeArrayWithRange = (end, start = 0, step = 1) =>
-  Array.from({ length: Math.ceil((end + 1 - start) / step) }).map((v, i) => i * step + start);
-
initializeArrayWithRange(5); // [0,1,2,3,4,5]
-initializeArrayWithRange(7, 3); // [3,4,5,6,7]
-initializeArrayWithRange(9, 0, 2); // [0,2,4,6,8]
-

toSafeInteger

Converts a value to a safe integer.

Use Math.max() and Math.min() to find the closest safe value. Use Math.round() to convert to an integer.

const toSafeInteger = num =>
-  Math.round(Math.max(Math.min(num, Number.MAX_SAFE_INTEGER), Number.MIN_SAFE_INTEGER));
-
toSafeInteger('3.2'); // 3
-toSafeInteger(Infinity); // 9007199254740991
+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
3227
commits
20016
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:
 
equals
Performs a deep comparison between two values to determine if they are equivalent.
Check if the two values are identical, if they are both Date objects with the same time, using Date.getTime() or if they are both non-object values with an equivalent value (strict comparison). Check if only one value is null or undefined or if their prototypes differ. If none of the above conditions are met, use Object.keys() to check if both values have the same number of keys, then use Array.every() to check if every key in the first value exists in the second one and if they are equivalent by calling this method recursively.
const equals = (a, b) => {
+  if (a === b) return true;
+  if (a instanceof Date && b instanceof Date) return a.getTime() === b.getTime();
+  if (!a || !b || (typeof a != 'object' && typeof b !== 'object')) return a === b;
+  if (a === null || a === undefined || b === null || b === undefined) return false;
+  if (a.prototype !== b.prototype) return false;
+  let keys = Object.keys(a);
+  if (keys.length !== Object.keys(b).length) return false;
+  return keys.every(k => equals(a[k], b[k]));
+};
+
equals({ a: [2, { e: 3 }], b: [4], c: 'foo' }, { a: [2, { e: 3 }], b: [4], c: 'foo' }); // true
+
isValidJSON
Checks if the provided argument is a valid JSON.
Use JSON.parse() and a try... catch block to check if the provided argument is a valid JSON.
const isValidJSON = obj => {
+  try {
+    JSON.parse(obj);
+    return true;
+  } catch (e) {
+    return false;
+  }
+};
+
isValidJSON('{"name":"Adam","age":20}'); // true
+isValidJSON('{"name":"Adam",age:"20"}'); // false
+isValidJSON(null); // true
+
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
 

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.