From 2ac51f2bde6e5463feea17fce2dfd6c102997c48 Mon Sep 17 00:00:00 2001 From: 30secondsofcode <30secondsofcode@gmail.com> Date: Tue, 7 Aug 2018 19:55:05 +0000 Subject: [PATCH] Travis build: 200 [cron] --- docs/index.html | 56 +- test/testlog | 3292 +++++++++++++++++++++++------------------------ 2 files changed, 1681 insertions(+), 1667 deletions(-) diff --git a/docs/index.html b/docs/index.html index 8d72d053f..39ddf2722 100644 --- a/docs/index.html +++ b/docs/index.html @@ -1,27 +1,41 @@ -30 seconds of code

logo 30 seconds of code

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

319
snippets

122
contributors

3504
commits

21278
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:

findLastIndex

Returns the index of the last element for which the provided function returns a truthy value.

Use Array.map() to map each element to an array with its index and value. Use Array.filter() to remove elements for which fn returns falsey values, Array.pop() to get the last one.

const findLastIndex = (arr, fn) =>
-  arr
-    .map((val, i) => [i, val])
-    .filter(([i, val]) => fn(val, i, arr))
-    .pop()[0];
-
findLastIndex([1, 2, 3, 4], n => n % 2 === 1); // 2 (index of the value 3)
-

hasClass

Returns true if the element has the specified class, false otherwise.

Use element.classList.contains() to check if the element has the specified class.

const hasClass = (el, className) => el.classList.contains(className);
-
hasClass(document.querySelector('p.special'), 'special'); // true
-

luhnCheck

Implementation of the Luhn Algorithm used to validate a variety of identification numbers, such as credit card numbers, IMEI numbers, National Provider Identifier numbers etc.

Use String.split(''), Array.reverse() and Array.map() in combination with parseInt() to obtain an array of digits. Use Array.splice(0,1) to obtain the last digit. Use Array.reduce() to implement the Luhn Algorithm. Return true if sum is divisible by 10, false otherwise.

const luhnCheck = num => {
-  let arr = (num + '')
-    .split('')
-    .reverse()
-    .map(x => parseInt(x));
-  let lastDigit = arr.splice(0, 1)[0];
-  let sum = arr.reduce((acc, val, i) => (i % 2 !== 0 ? acc + val : acc + ((val * 2) % 9) || 9), 0);
-  sum += lastDigit;
-  return sum % 10 === 0;
+30 seconds of code
logo 30 seconds of code
Curated collection of useful JavaScript snippets
that you can understand in 30 seconds or less.
319
snippets
122
contributors
3505
commits
21291
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:
 
hz
Returns the number of times a function executed per second. hz is the unit for hertz, the unit of frequency defined as one cycle per second.
Use performance.now() to get the difference in milliseconds before and after the iteration loop to calculate the time elapsed executing the function iterations times. Return the number of cycles per second by converting milliseconds to seconds and dividing it by the time elapsed. Omit the second argument, iterations, to use the default of 100 iterations.
const hz = (fn, iterations = 100) => {
+  const before = performance.now();
+  for (let i = 0; i < iterations; i++) fn();
+  return (1000 * iterations) / (performance.now() - before);
 };
-
luhnCheck('4485275742308327'); // true
-luhnCheck(6011329933655299); //  false
-luhnCheck(123456789); // false
+
// 10,000 element array
+const numbers = Array(10000)
+  .fill()
+  .map((_, i) => i);
+
+// Test functions with the same goal: sum up the elements in the array
+const sumReduce = () => numbers.reduce((acc, n) => acc + n, 0);
+const sumForLoop = () => {
+  let sum = 0;
+  for (let i = 0; i < numbers.length; i++) sum += numbers[i];
+  return sum;
+};
+
+// `sumForLoop` is nearly 10 times faster
+Math.round(hz(sumReduce)); // 572
+Math.round(hz(sumForLoop)); // 4784
+
redirect
Redirects to a specified URL.
Use window.location.href or window.location.replace() to redirect to url. Pass a second argument to simulate a link click (true - default) or an HTTP redirect (false).
const redirect = (url, asLink = true) =>
+  asLink ? (window.location.href = url) : window.location.replace(url);
+
redirect('https://google.com');
+
size
Get size of arrays, objects or strings.
Get type of val (array, object or string). Use length property for arrays. Use length or size value if available or number of keys for objects. Use size of a Blob object created from val for strings.
Split strings into array of characters with split('') and return its length.
const size = val =>
+  Array.isArray(val)
+    ? val.length
+    : val && typeof val === 'object'
+      ? val.size || val.length || Object.keys(val).length
+      : typeof val === 'string'
+        ? new Blob([val]).size
+        : 0;
+
size([1, 2, 3, 4, 5]); // 5
+size('size'); // 4
+size({ one: 1, two: 2, three: 3 }); // 3
 

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.