Notes on software and the ideas behind it

Find the meaning
behind the code.

I’m Fred Yang. I write about software—how it works, why it behaves the way it does, and the ideas that make code easier to reason about.

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Working notes / 2026

Recently mapped

Architecture, reactivity, and the hidden relationships that shape frontend systems.

field note

Observable with async pipe used multiple times in Angular template

There is a question in stackoverlfow Angular - Observable with async pipe used multiple times in template… Good Practice or Bad?
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field note

Demystifying the syntax of structural directive

Structural directive is a special directive. Angular comes with a couple of them such as ngIf, ngFor. Angular provides detailed documentation about the structural directive. There are two syntaxes to use a directive, the...
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field note

Hello Jekyll!

I haven’t written any blog for 3 years, because the blogger platform does not provide markdown support. Now that I have migrated it to Jekyll, and let’s blog!
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javascript

Array(n) constructor

JavaScript Array constructor can be used in the follow syntax. const items1 = new Array(2); //(2) [empty × 2] //or const items2 = Array(2); //(2) [empty × 2]
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typescript

Demystify typescript keyword type and typeof

In typescript, keyword 'type' is used to alias existing types or anonymous types. This is typescript feature, and it has nothing to do with JavaScript. While const/let are used to declare variable in JavaScript....
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