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.
Open the notebookWorking notes / 2026
Recently mapped
Architecture, reactivity, and the hidden relationships that shape frontend systems.
javascript
apply() and call()
v3 defines two methods that are defined for all functions, call( ) and apply( ). These methods allow you to invoke a function as if it were a method of some other object. The...
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javascript
Primitive Types and Reference Types
Numbers, boolean values, and the null and undefined types are primitive. Objects, arrays, and functions are reference types.
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javascript
null vs undefined
In javascript, they are different concept.
var d ={};
d.x = null;
alert(d.x); //null
alert(d.y); //undefined
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javascript
Javascript notes
Object Creation
<p>When a function used with new, it became a constructor</p>
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xslt