ES6 JavaScript Code Snippets

Taken from 30secondsofcode

1.How to hide all elements specified?

const hide = (elementList) => [...el].forEach(e => (e.style.display = 'none'));

// Example
hide(document.querySelectorAll('img')); // Hides all <img> elements on the page

// or
const hide = (...el) => [...el].forEach(e => (e.style.display = 'none'));
hide(...document.querySelectorAll('img'));

2.How to check if the element has the specified class?

const hasClass = (el, className) => el.classList.contains(className);

// Example
hasClass(document.querySelector('p.special'), 'special'); // true

3.How to toggle a class for an element?

const toggleClass = (el, className) => el.classList.toggle(className);

// Example
toggleClass(document.querySelector('p.special'), 'special');
// The paragraph will not have the 'special' class anymore

4.How to get the scroll position of the current page?

const getScrollPosition = (el = window) => ({
x: el.pageXOffset !== undefined ? el.pageXOffset : el.scrollLeft,
y: el.pageYOffset !== undefined ? el.pageYOffset : el.scrollTop
});

// Example
getScrollPosition(); // {x: 0, y: 200}

5.How to smooth-scroll to the top of the page?

const scrollToTop = () => {
const c = document.documentElement.scrollTop || document.body.scrollTop;
if (c > 0) {
window.requestAnimationFrame(scrollToTop);
window.scrollTo(0, c - c / 8);
}
};

// Example
scrollToTop();

6.How to check if the parent element contains the child element?

const elementContains = (parent, child) => parent !== child && parent.contains(child);

// Examples
elementContains(document.querySelector('head'), document.querySelector('title'));
// true
elementContains(document.querySelector('body'), document.querySelector('body')); // false

7.How to check if the element specified is visible in the viewport?

const elementIsVisibleInViewport = (el, partiallyVisible = false) => {
const { top, left, bottom, right } = el.getBoundingClientRect();
const { innerHeight, innerWidth } = window;
return partiallyVisible
? ((top > 0 && top < innerHeight) || (bottom > 0 && bottom < innerHeight)) &&
((left > 0 && left < innerWidth) || (right > 0 && right < innerWidth))
: top >= 0 && left >= 0 && bottom <= innerHeight && right <= innerWidth;
};

// Examples
elementIsVisibleInViewport(el); // (not fully visible)
elementIsVisibleInViewport(el, true); // (partially visible)

8.How to fetch all images within an element?

const getImages = (el, includeDuplicates = false) => {
const images = [...el.getElementsByTagName('img')].map(img => img.getAttribute('src'));
return includeDuplicates ? images : [...new Set(images)];
};

// Examples
getImages(document, true); // ['image1.jpg', 'image2.png', 'image1.png', '...']
getImages(document, false); // ['image1.jpg', 'image2.png', '...']

9.How to figure out if the device is a mobile device or a desktop/laptop?

const detectDeviceType = () =>
/Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent)
? 'Mobile'
: 'Desktop';

// Example
detectDeviceType(); // "Mobile" or "Desktop"

10.How to get the current URL?

const currentURL = () => window.location.href;

// Example
currentURL(); // 'https://google.com'

11.How to create an object containing the parameters of the current URL?

const getURLParameters = url =>
(url.match(/([^?=&]+)(=([^&]*))/g) || []).reduce(
(a, v) => ((a[v.slice(0, v.indexOf('='))] = v.slice(v.indexOf('=') + 1)), a),
{}
);

// Examples
getURLParameters('http://url.com/page?n=Adam&s=Smith'); // {n: 'Adam', s: 'Smith'}
getURLParameters('google.com'); // {}

12.How to encode a set of form elements as an object?

const formToObject = form =>
Array.from(new FormData(form)).reduce(
(acc, [key, value]) => ({
...acc,
[key]: value
}),
{}
);

// Example
formToObject(document.querySelector('#form')); // { email: 'test@email.com', name: 'Test Name' }

13.How to retrieve a set of properties indicated by the given selectors from an object?

const get = (from, ...selectors) =>
[...selectors].map(s =>
s
.replace(/\[([^\[\]]*)\]/g, '.$1.')
.split('.')
.filter(t => t !== '')
.reduce((prev, cur) => prev && prev[cur], from)
);
const obj = { selector: { to: { val: 'val to select' } }, target: [1, 2, { a: 'test' }] };

// Example
get(obj, 'selector.to.val', 'target[0]', 'target[2].a'); // ['val to select', 1, 'test']

14.How to invoke the provided function after wait (in milliseconds)?

const delay = (fn, wait, ...args) => setTimeout(fn, wait, ...args);
delay(
function(text) {
console.log(text);
},
1000,
'later'
);

// Logs 'later' after one second.

15.How to trigger a specific event on a given element, optionally passing custom data?

const triggerEvent = (el, eventType, detail) =>
el.dispatchEvent(new CustomEvent(eventType, { detail }));

// Examples
triggerEvent(document.getElementById('myId'), 'click');
triggerEvent(document.getElementById('myId'), 'click', { username: 'bob' });

16.How to remove an event listener from an element?

const off = (el, evt, fn, opts = false) => el.removeEventListener(evt, fn, opts);

const fn = () => console.log('!');
document.body.addEventListener('click', fn);
off(document.body, 'click', fn); // no longer logs '!' upon clicking on the page

17.How to get readable format of the given number of milliseconds?

const formatDuration = ms => {
if (ms < 0) ms = -ms;
const time = {
day: Math.floor(ms / 86400000),
hour: Math.floor(ms / 3600000) % 24,
minute: Math.floor(ms / 60000) % 60,
second: Math.floor(ms / 1000) % 60,
millisecond: Math.floor(ms) % 1000
};
return Object.entries(time)
.filter(val => val[1] !== 0)
.map(([key, val]) => `${val} ${key}${val !== 1 ? 's' : ''}`)
.join(', ');
};

// Examples
formatDuration(1001); // '1 second, 1 millisecond'
formatDuration(34325055574); // '397 days, 6 hours, 44 minutes, 15 seconds, 574 milliseconds'

18.How to get the difference (in days) between two dates?

const getDaysDiffBetweenDates = (dateInitial, dateFinal) =>
(dateFinal - dateInitial) / (1000 * 3600 * 24);

// Example
getDaysDiffBetweenDates(new Date('2017-12-13'), new Date('2017-12-22')); // 9

19.How to make a GET request to the passed URL?

const httpGet = (url, callback, err = console.error) => {
const request = new XMLHttpRequest();
request.open('GET', url, true);
request.onload = () => callback(request.responseText);
request.onerror = () => err(request);
request.send();
};

httpGet(
'https://jsonplaceholder.typicode.com/posts/1',
console.log
);

// Logs: {"userId": 1, "id": 1, "title": "sample title", "body": "my text"}

20.How to make a POST request to the passed URL?

const httpPost = (url, data, callback, err = console.error) => {
const request = new XMLHttpRequest();
request.open('POST', url, true);
request.setRequestHeader('Content-type', 'application/json; charset=utf-8');
request.onload = () => callback(request.responseText);
request.onerror = () => err(request);
request.send(data);
};

const newPost = {
userId: 1,
id: 1337,
title: 'Foo',
body: 'bar bar bar'
};
const data = JSON.stringify(newPost);
httpPost(
'https://jsonplaceholder.typicode.com/posts',
data,
console.log
);

// Logs: {"userId": 1, "id": 1337, "title": "Foo", "body": "bar bar bar"}

21.How to create a counter with the specified range, step and duration for the specified selector?

const counter = (selector, start, end, step = 1, duration = 2000) => {
let current = start,
_step = (end - start) * step < 0 ? -step : step,
timer = setInterval(() => {
current += _step;
document.querySelector(selector).innerHTML = current;
if (current >= end) document.querySelector(selector).innerHTML = end;
if (current >= end) clearInterval(timer);
}, Math.abs(Math.floor(duration / (end - start))));
return timer;
};

// Example
counter('#my-id', 1, 1000, 5, 2000); // Creates a 2-second timer for the element with id="my-id"

22.How to copy a string to the clipboard?

const copyToClipboard = str => {
const el = document.createElement('textarea');
el.value = str;
el.setAttribute('readonly', '');
el.style.position = 'absolute';
el.style.left = '-9999px';
document.body.appendChild(el);
const selected =
document.getSelection().rangeCount > 0 ? document.getSelection().getRangeAt(0) : false;
el.select();
document.execCommand('copy');
document.body.removeChild(el);
if (selected) {
document.getSelection().removeAllRanges();
document.getSelection().addRange(selected);
}
};

// Example
copyToClipboard('Lorem ipsum'); // 'Lorem ipsum' copied to clipboard.

23.How to find out if the browser tab of the page is focused?

const isBrowserTabFocused = () => !document.hidden;

// Example
isBrowserTabFocused(); // true

24.How to create a directory, if it does not exist?

const fs = require('fs');
const createDirIfNotExists = dir => (!fs.existsSync(dir) ? fs.mkdirSync(dir) : undefined);

// Example
createDirIfNotExists('test'); // creates the directory 'test', if it doesn't exist

Containerize a .NET Core app

Essential commands

Docker has many different commands that create, manage, and interact with containers and images. These Docker commands are essential to managing your containers:

Here an example:
https://docs.microsoft.com/en-us/dotnet/core/docker/build-container

(from Visual Studio 2019 it is possible to add Docker support):

Opzione di menu Aggiungi Supporto Docker in Visual Studio

Useful regex

\/\*.*\*\/

\/ matches the character “/” literally (case sensitive)
\* matches the character “*” literally (case sensitive)
.* matches any character (except for line terminators)
* Quantifier — Matches between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\* matches the character “*” literally (case sensitive)
\/ matches the character “/” literally (case sensitive)

i.e.
/* 501 */
/* 1 */

Reset a single file to a specific commit

Assuming the hash of the commit you want is c5f567:

git checkout c5f567 -- file1/to/restore file2/to/restore

The git checkout man page gives more information.

If you want to revert to the commit before c5f567, append ~1 (where 1 is the number of commits you want to go back, it can be anything):

git checkout c5f567~1 -- file1/to/restore file2/to/restore

As a side note, I’ve always been uncomfortable with this command because it’s used for both ordinary things (changing between branches) and unusual, destructive things (discarding changes in the working directory).

Search and rename Foreign Key Name

List foreign keys:

select schema_name(fk_tab.schema_id) + '.' + fk_tab.name as foreign_table, '>-' as rel, schema_name(pk_tab.schema_id) + '.' + pk_tab.name as primary_table, substring(column_names, 1, len(column_names)-1) as [fk_columns], fk.name as fk_constraint_name from sys.foreign_keys fk inner join sys.tables fk_tab on fk_tab.object_id = fk.parent_object_id inner join sys.tables pk_tab on pk_tab.object_id = fk.referenced_object_id cross apply (select col.[name] + ', ' from sys.foreign_key_columns fk_c inner join sys.columns col on fk_c.parent_object_id = col.object_id and fk_c.parent_column_id = col.column_id where fk_c.parent_object_id = fk_tab.object_id and fk_c.constraint_object_id = fk.object_id order by col.column_id for xml path ('') ) D (column_names) order by schema_name(fk_tab.schema_id) + '.' + fk_tab.name, schema_name(pk_tab.schema_id) + '.' + pk_tab.name

Search Primary keys:

SELECT KU.table_name as TABLENAME, column_name as PRIMARYKEYCOLUMN, KU.CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS AS TC INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE AS KU ON TC.CONSTRAINT_TYPE = 'PRIMARY KEY' AND TC.CONSTRAINT_NAME = KU.CONSTRAINT_NAME AND KU.table_name='Notes' ORDER BY KU.TABLE_NAME, KU.ORDINAL_POSITION;

Then rename the foreign key:

sp_rename @objname = N'PK_Notes_ADF019271172DFE', @newname = N'PK_Notes'

Update if parameter is not null or empty

Using just IsNull your query would look something like…

UPDATE [Users]
SET FirstName = IsNull(@FirstName, FirstName),
City = IsNull(@City, City)
....
WHERE ...

DECLARE @value AS INT = Null
SELECT CASE WHEN ISNULL(@value, 2)=0 THEN Null Else ISNULL(@value, 2) END

will Update the row with the param value if they are NOT null, otherwise update it to itself aka change nothing.

Software craftsmenship manifesto

From Creaftsmenship Manifesto

Background materials

Food for thought

Kata and exercises

Conferences and community

Get all documents from mongodb collection

Get all documents from a MongoDB collection:

Using the current version of the driver (v2.0) you can do that by passing a filter that matches everything:

var documents = await SpeCollection.Find(_ => true).ToListAsync();

They have also added an empty filter (FilterDefinition.Empty) which will arrive in the next version of the driver (v2.1):

var documents = await SpeCollection.Find(Builders.Filter.Empty).ToListAsync();

With and without Lambda Expression

var id = 1;
var query =
from user in database.Users
join invoice in database.Invoices on user.Id equals invoice.UserId
where user.Id == id
select new { User = user, Invoice = invoice };

Here’s the same query, using Lambda Expression LINQ extension methods:

var id = 1;
var query = database.Users // your starting point - table in the "from" statement
.Join(database.Invoices, // the source table of the inner join
user => user.Id, // Select the primary key (the first part of the "on" clause in an sql "join" statement)
invoice => invoice.UserId, // Select the foreign key (the second part of the "on" clause)
(user, invoice) => new { User = user, Invoice = invoice }) // selection
.Where(userAndInvoice => userAndInvoice.User.Id == id); // where statement

Git workflow

Here you can see the basics workflow for git
After cloning your repo from any git platform provider Like github, gitlab, bitbucket etc… .
Firstly check branch:
git branch
(your base branch, most likely develop or master. Consider develop as a base branch)
Fetch latest remote code to local:
git pull
(for latest develop code)
Checkout new branch as per feature and
git checkout -b newBranchName
(If you are working on any new bug named branch feature than give branch name feature/ login-feature or you are working on any bug than give branch name bug/login-bug.
This way you can eaisily identify/judge your branch by name.)

After finish your work in your
$ git status (after Changes )
Add changed file into staging
git add . | | $ git add .. (dot) (for feature/bug branch.(in red colored) add file in staging)
Check staging file (in green colored)
$ git status
Add commit message
$ git commit -m Commit message
Checkout your base branch
$ git checkout develop (switch
For latest code (if other guy
$ git pull (for latest develop code)
Checkout your previous feature/to develop) working on it)
bug branch

git pull (for latest develop code)
Checkout your previous feature.
git checkout YOUR PREVIOUS_BRANCH
Rebase your branch with develop
git rebase develop
Push your feature/bug branch
git push
(it will suggest command if bug branch or master to remote: its not in remote).
After this open your git platform provider Like github, gitlab, bitbucket whatever you use.
Assign merge request to your other develop to review code, it will increase your productivity and code quality.