Internet Explorer 11 and Angular 2+ – Agilix – Medium

IE 11 and Angular don’t always mix. I must say that there’s quite the support provided by the Angular dev team and community. But, there are things that really aren’t up for the Angular devs to fix.

I’ve created a small list of issues I’ve encountered when developing and Angular 5 application for an IE 11 client.

Source: Internet Explorer 11 and Angular 2+ – Agilix – Medium

Javascript debugging helper – Count number of eventlisteners in Chrome console

Paste and run one of the code blocks below in chrome console to get eventlisteners count.

//eventlisteners counter - grouped summary
Array.from(document.querySelectorAll('*'))  .reduce(function(pre, dom){
    var evtObj = getEventListeners(dom)
    Object.keys(evtObj).forEach(function (evt) {
      if (typeof pre[evt] === 'undefined') {
        pre[evt] = 0
      }
      pre[evt] += evtObj[evt].length
    })
    return pre
  }, {})
  
//_-------------------------------------------
  
  // //eventlisteners - totalcount
  var totalCount = 0;
  Array.from(document.querySelectorAll('*')).reduce(function(pre, dom){
    var evtObj = getEventListeners(dom)
    Object.keys(evtObj).forEach(function (evt) {
      if (typeof pre[evt] === 'undefined') {
        pre[evt] = 0
      }
      // pre[evt] += evtObj[evt].length
	  totalCount += evtObj[evt].length;
    })
    return totalCount;
  }, {})
  
  
  //---------------------------------------

 

Angular: Tips. The importance of Pipes – codeburst

What we all like in Angular primarily is that it all mostly about templates. Templates are smart, dynamic, they use change detection to update themselves on a moment’s notice when a model is updated, the can manage HTML elements and nested components, enrich the markup with directives and make on-the fly data transformations, and the template syntax is amazing. The tools provided are vast and rich, but is it up to us to use them wisely.

Source: Angular: Tips. The importance of Pipes – codeburst

How to avoid website jank: a lot of performance tips

We see more and more websites that do not care of the performances.
They are slow, fat, embed lots of resources, make you download several MBs, are not fluid when you scroll down, are not fluid when you click on something, are not responsive, have slow animations. It’s easy to make a website, but it’s harder to make it good. A slow website will have a big churn in its users, because the navigation was crappy.
www.sderosiaux.com/articles/2015/03/01/perfmatters/

jasmine parameterized unit test – Stack Overflow

Based on piotrek’s answer and the article Parameterized testing in Javascript, you could also use the following approach which uses ES6 syntax:

[ 
['abc', 3], 
['ab', 2], 
['', 0],
].forEach(([string, expectedLength]) => { 
it(`should return length ${expectedLength} for string "${string}"`, 
() => { expect(string.length).toBe(expectedLength); });
});

I have tested it with the Jest test framework, but it should work with Jasmine as well.

Source: jasmine parameterized unit test – Stack Overflow

VSCode Dark+ theme and colourings for WebStorm

This looks great, VS Code Dark+ theme:
lenny1882/vscode-dark-plus-webstorm: VSCode Dark+ theme and colourings for WebStorm

Another alternative (not tested) :
http://color-themes.com/?view=theme&id=57b63a1c849f3a1800dc1a1f

This one might be a good alternative (Dracula theme):
https://draculatheme.com/visual-studio-code/
https://draculatheme.com/jetbrains/

How to use underscore lib from DefinitelyTyped with typescript? – Stack Overflow

Step 1. install type definitions (e.g. vs code intellisense) to project:
npm install –save @types/underscore

(https://www.npmjs.com/package/@types/underscore)

 

Step 2. import to ts file:

import * as _ from “underscore”;

Source: How to use underscore lib from DefinitelyTyped with typescript? – Stack Overflow

TypeScript vs. C#: LINQ

TypeScript counterparts for C# LINQ.

Source: TypeScript vs. C#: LINQ
All of below are copied from https://decembersoft.com in case that blog post disappears in future, I save it here for time keeping. Let me know if its a problem.

TypeScript has no equivalent for the language-integrated-natural-query aspect of LINQ. (hey, isn’t that literally the whole acronym?)

True, you can’t write the following LINQ statement in TypeScript

var adultUserNames =  from u in users  where u.Age >= 18  select u.Name;

However, the IEnumerable<T> extension methods, which are at the heart of LINQ, have equivalents in TypeScript (or can be emulated).

Aggregate

// C#var leftToRight = users.Aggregate(initialValue, (a, u) => /* ... */);
// TypeScriptconst leftToRight = users.reduce((a, u) => /* ... */, initialValue);const rightToLeft = users.reduceRight((a, u) => /* ... */, initialValue);

All

// C#var allReady = users.All(u => u.IsReady);
// TypeScriptconst allReady = users.every(u => u.isReady);

Any

// C#var isDirty = users.Any(u => u.IsDirty);
// TypeScriptconst isDirty = users.some(u => u.isDirty);

Append

// C#var allUsers = users.Append(oneMoreUser);
// TypeScriptconst allUsers = [ ...users, oneMoreUser ];

Average

// C#var avgAge = users.Average(u => u.Age);
// TypeScriptif (users.length < 1) {  throw new Error('source contains no elements');}const avgAge = users.reduce((a, u) => a + u.age, 0) / users.length;

Cast

// C#var people = users.Cast<Person>();
// TypeScriptconst people = users as Person[];// Note: not semantically the same. The C# version throws an exception// if any of the users can't be cast to type Person.

Concat

// C#var allUsers = users.Concat(moreUsers);
// TypeScriptconst allUsers = [ ...users, ...moreUsers ];

Contains

// C#var hasAdmin = users.Contains(admin);
// TypeScriptconst hasAdmin = users.includes(admin); // Use a polyfill for IE support

Count

// C#var n = users.Count();
// TypeScriptconst n = users.length;

DefaultIfEmpty

// C#var nonEmptyUsers = Enumerable.DefaultIfEmpty(users);
// TypeScriptconst nonEmptyUsers = users.length ? users : [ null ];

Distinct

// C#var uniqueNames = users.Select(u => u.Name).Distinct();
// TypeScriptconst uniqueNames = Object.keys(  users.map(u => u.name).reduce(    (un, u) => ({ ...un, n }),    {}  ));

ElementAt

// C#var nth = users.ElementAt(n);
// TypeScriptif (n < 0 || n > users.length) {  throw new Error('Index was out of range');}const nth = users[n];

ElementAtOrDefault

// C#var nth = users.ElementAtOrDefault(n);
// TypeScriptconst nth = users[n];

Empty

// C#var noUsers = IEnumerable.Empty<User>();
// TypeScriptconst noUsers: User[] = [];const noUsers = [] as User[];

Except

// C#var maleUsers = users.Except(femaleUsers);
// TypeScriptconst maleUsers = users.filter(u =>  !femaleUsers.includes(u) // Use a polyfill for IE support);

First

// C#var first = users.First();
// TypeScriptif (users.length < 1) {  throw new Error('Sequence contains no elements');}const first = users[0];

FirstOrDefault

// C#var first = users.FirstOrDefault();
// TypeScriptconst first = users[0];

List.ForEach

// C#users.ToList().ForEach(u => /* ... */);
// TypeScriptusers.forEach(u => /* ... */);

GroupBy

// C#var usersByCountry = users.GroupBy(u => u.Country);
// TypeScriptconst usersByCountry = users.reduce((ubc, u) => ({  ...ubc,  [u.country]: [ ...(ubc[u.country] || []), u ],}), {});

Intersect

// C#var targetUsers = usersWhoClicked.Intersect(usersBetween25And45);
// TypeScriptconst targetUsers = usersWhoClicked.filter(u =>  usersBetween25And45.includes(u) // Use a polyfill for IE support);

Last

// C#var last = users.Last();
// TypeScriptif (users.length < 1) {  throw new Error('Sequence contains no elements');}const last = users[users.length - 1];

LastOrDefault

// C#var last = users.LastOrDefault();
// TypeScriptconst last = users[users.length - 1];

Max

// C#var oldestAge = users.Max(u => u.Age);
// TypeScriptif (users.length < 1) {  throw new Error('source contains no elements');}const oldestAge = users.reduce((oa, u) => Math.max(oa, u.age), 0);

Min

// C#var youngestAge = users.Min(u => u.Age);
// TypeScriptif (users.length < 1) {  throw new Error('source contains no elements');}const youngestAge = users.reduce((ya, u) => Math.min(ya, u.age), Number.MAX_VALUE);

OfType

// C#var bots = users.OfType<Bot>();
// TypeScript// No equivalent

OrderBy / ThenBy

// C#var sorted = users.OrderBy(u => u.Age).ThenBy(u => u.Name);
// TypeScriptconst sorted = users.sort((a, b) => {  const ageDiff = b.age - a.age;  if (ageDiff) return ageDiff;  return a.name.localeCompare(b.name); // Use a polyfill for IE support});

Reverse

// C#var backwards = users.Reverse();
// TypeScriptconst backwards = users.reverse();// Caution: users is also reversed!

Select

// C#var names = users.Select(u => u.Name);
// TypeScriptconst names = users.map(u => u.name);

SelectMany

// C#var phoneNumbers = users.SelectMany(u => u.PhoneNumbers);
// TypeScriptconst phoneNumbers = users.reduce((pn, u) => [ ...pn, ...u.phoneNumbers ], []);

Single

// C#var user = users.Single();
// TypeScriptif (users.length > 1) {  throw new Error('The input sequence contains more than one element');}else if (!users.length) {  throw new Error('The input sequence is empty');}const user = users[0];

SingleOrDefault

// C#var user = users.Single();
// TypeScriptconst user = users[0];

Skip

// C#var otherUsers = users.Skip(n);
// TypeScriptconst otherUsers = users.filter((u, i) => i >= n);

SkipWhile

// C#var otherUsers = users.SkipWhile(predicate);
// TypeScriptlet i = 0;while (i < users.length && predicate(users[i++]));const otherUsers = users.slice(i - 1);

Sum

// C#var totalYears = users.Sum(u => u.Age);
// TypeScriptif (users.length < 1) {  throw new Error('source contains no elements');}const totalYears = users.reduce((ty, u) => ty + u, 0);

Take

// C#var otherUsers = users.Take(n);
// TypeScriptconst otherUsers = users.filter((u, i) => i < n);

TakeWhile

// C#var otherUsers = users.TakeWhile(predicate);
// TypeScriptlet i = 0;while (i < users.length && predicate(users[i++]));const otherUsers = users.slice(0, i - 1);

Union

// C#var allUsers = someUser.Union(otherUsers);
// TypeScriptconst allUsers = otherUsers.reduce((au, u) =>   au.includes(u) // Use a polyfill for IE support    ? au    : [ ...au, u ]}), someUsers));

Where

// C#var adults = users.Where(u => u.Age >= 18);
// TypeScriptconst adults = users.filter(u => u.age >= 18);

Zip

// C#var matches = buyers.Zip(sellers, (b, s) => new { Buyer = b, Seller = s });
// TypeScriptconst matches = [];for (let i = 0; i < buyers.length && i < sellers.length; i++) {  matches.push({    buyer: buyers[i],    seller: sellers[i],  });}