From time to time I get possesed by an idea, which I want to implement. It is almost like if that idea was forcing me to make it happen. When this happens I can barely wait till the morning, so I can start coding and at least test, if that idea is doable. I had …
Tag Archives: programming
Do not throw Error in constructors
Suppose that you need to instantiate a class, which takes some dependencies as parameters in constructor. I am mostly using Angular, so those dependencies are some injectable services in my case. Something like this: What do you think will happen if you try to instantiate this class? What will happen with that Error? How will …
Frozen global object
If your app uses global object as a config, you should make sure, that this object is truly readonly. So that an attacker can not modify it in dev console. This is how to do it. // example of frozen global object // freeze the config object properties const config = Object.freeze({ httpApi: ‘http://127.0.0.1:20003/v1’, wsApi: …
Custom command line shortcuts with Doskey
I’ve learned this nice trick from Petr Horáček aka Besir while working on Nakamotox. So the credit goes to him. You can define custom commands via doskey (only on Windows) and then invoke them via command line. It is quite powerfull, because you can define alias for command with predefined attributes, so it save you lot of repetitive …
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Email validator for Angular
Angular has built in email validator, but it is very benevolent one. It allows for single letter domains, therefore email a@b is considered valid. Their motivation is that when used in intranet it can be perfectly valid email, because you can have custom domain names. But it does not make much sense in the broader …
Workaround for ExpressionChangedAfterItHasBeenCheckedError in async pipe
Imagine that you have this piece of code, where userInfo$ is Observable and it value is not yet emitted. <app-change-email [currentEmail]=”(userInfo$ | async).user.email”></app-change-email> The code works, but it will report error ExpressionChangedAfterItHasBeenCheckedError to the console (only in dev mode). That is because the component has received the value, but the value has changed later. Angular …
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Angular custom event bubbling
Custom events in Angular by default do not bubble up. It is because they are not really events, they are based on EventEmitter, which is similar to pub/sub mechanism. You can read lengthy discussion about it on Angular’s Github. Unfortunately the examples provided by Angular team often mention $event as named parameter in the event listener, …
ES6 generators and async/await
Motivation for this blogpost was my initial ignorance regarding the upcoming ES6 and the generator function. Around christmas 2015 I was looking for a new job, and during one of the assigned test-jobs I had to use generator functions, the .co library, two different databases (one SQL and the other NoSQL) and node.js. I failed, …
Sticky header menu with animation using Javascript
The problem I needed to create animated menu, which will stay always sticked to the top and will collapse or expand as user scroll How it should look Click the image for a live version – Wisephora.com What do you need to implement it? You will need a little bit Javascript and CSS. There are several …
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Debounced actions in EmberJs
I was developing EmberJS component based on input field. It’s main purpose was auto-save when user stops typing. That is a typing use-case for debounce and should be easy and straightforward. Right? Well, since I am new to Ember, it was not so easy for me. It was more like a riddle and it took …