30 seconds of code
Curated collection of useful JavaScript snippets
that you can understand in 30 seconds or less.
30 seconds of codeCurated collection of useful JavaScript snippets
that you can understand in 30 seconds or less.
319
snippets
122
contributors
3510
commits
21310
stars
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.
Our sophisticated robot helpers pick new snippets from our collection daily, so that you can discover new snippets to enhance your projects:
Converts the given array elements into <li> tags and appends them to the list of the given id.
Use Array.map(), document.querySelector(), and an anonymous inner closure to create a list of html tags.
const arrayToHtmlList = (arr, listID) => - (el => ( - (el = document.querySelector('#' + listID)), - (el.innerHTML += arr.map(item => `<li>${item}</li>`).join('')) - ))(); -
arrayToHtmlList(['item 1', 'item 2'], 'myListID'); -
Returns the native type of a value.
Returns lowercased constructor name of value, "undefined" or "null" if value is undefined or null.
const getType = v => - v === undefined ? 'undefined' : v === null ? 'null' : v.constructor.name.toLowerCase(); -
getType(new Set([1, 2, 3])); // 'set' -
Joins all elements of an array into a string and returns this string. Uses a separator and an end separator.
Use Array.reduce() to combine elements into a string. Omit the second argument, separator, to use a default separator of ','. Omit the third argument, end, to use the same value as separator by default.
const join = (arr, separator = ',', end = separator) => - arr.reduce( - (acc, val, i) => - i === arr.length - 2 - ? acc + val + end - : i === arr.length - 1 - ? acc + val - : acc + val + separator, - '' - ); -
join(['pen', 'pineapple', 'apple', 'pen'], ',', '&'); // "pen,pineapple,apple&pen" -join(['pen', 'pineapple', 'apple', 'pen'], ','); // "pen,pineapple,apple,pen" -join(['pen', 'pineapple', 'apple', 'pen']); // "pen,pineapple,apple,pen" -
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:
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!
Start by creating a snippet, according to the snippet template. Make sure to follow these simple guidelines:
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.
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.
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.
30 seconds of codeCurated collection of useful JavaScript snippets
that you can understand in 30 seconds or less.
319
snippets
122
contributors
3518
commits
21322
stars
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.
Our sophisticated robot helpers pick new snippets from our collection daily, so that you can discover new snippets to enhance your projects:
Flattens an array up to the specified depth.
Use recursion, decrementing depth by 1 for each level of depth. Use Array.reduce() and Array.concat() to merge elements or arrays. Base case, for depth equal to 1 stops recursion. Omit the second argument, depth to flatten only to a depth of 1 (single flatten).
const flatten = (arr, depth = 1) => + arr.reduce((a, v) => a.concat(depth > 1 && Array.isArray(v) ? flatten(v, depth - 1) : v), []); +
flatten([1, [2], 3, 4]); // [1, 2, 3, 4] +flatten([1, [2, [3, [4, 5], 6], 7], 8], 2); // [1, 2, 3, [4, 5], 6, 7, 8] +
Replaces all but the last num of characters with the specified mask character.
Use String.slice() to grab the portion of the characters that need to be masked and use String.replace() with a regexp to replace every character with the mask character. Concatenate the masked characters with the remaining unmasked portion of the string. Omit the second argument, num, to keep a default of 4 characters unmasked. If num is negative, the unmasked characters will be at the start of the string. Omit the third argument, mask, to use a default character of '*' for the mask.
const mask = (cc, num = 4, mask = '*') => + ('' + cc).slice(0, -num).replace(/./g, mask) + ('' + cc).slice(-num); +
mask(1234567890); // '******7890' +mask(1234567890, 3); // '*******890' +mask(1234567890, -4, ' +
+
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:
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!
Start by creating a snippet, according to the snippet template. Make sure to follow these simple guidelines:
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.
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.
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.
