// field notes on javascript & the web
Practical writing on JavaScript, tooling, and the modern web.
Working notes on the parts of front-end development that age well: the language itself, how it runs in the browser, and the tools that keep a codebase honest.
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Featured
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Language and patterns
A Field Guide to JavaScript Array Methods
map, filter, and reduce replace most hand-written loops with clearer intent. A practical tour of the array methods worth reaching for, and when a…
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Browser and runtime
Working with the DOM Without a Framework
The browser ships a capable API for selecting elements, handling events, and updating the page. A refresher on doing it directly with modern DOM…
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Tooling and quality
A Practical Approach to JavaScript Testing
What to test, how the common kinds of tests differ, and how a modern test runner turns a vague intention to test into a…
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Tooling and quality
Debugging JavaScript in the Browser
The browser devtools are a full debugger most developers barely use. Breakpoints, the call stack, watch expressions, and the network panel beat scattered logging.
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Language and patterns
Objects and Classes in JavaScript: Prototypes and Composition
JavaScript objects work differently from classical languages. A look at prototypes, the class syntax built on top of them, and when composition beats inheritance.
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Language & patterns
03 · entries-
A Field Guide to JavaScript Array Methods
map, filter, and reduce replace most hand-written loops with clearer intent. A practical tour of the array methods worth reaching for, and when a loop still wins.
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Objects and Classes in JavaScript: Prototypes and Composition
JavaScript objects work differently from classical languages. A look at prototypes, the class syntax built on top of them, and when composition beats inheritance.
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JavaScript Modules and Packages: From Script Tags to ESM
How JavaScript moved from global script tags and ad-hoc registries to native ES modules and a package manager, and what that means for everyday code.
Browser & runtime
03 · entries-
Working with the DOM Without a Framework
The browser ships a capable API for selecting elements, handling events, and updating the page. A refresher on doing it directly with modern DOM methods.
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Promises, async/await, and the Event Loop
JavaScript runs on a single thread yet handles many things at once. The event loop, the task queues, and where promises fit explain how that works.
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Data Fetching in the Browser: From XMLHttpRequest to fetch
How browsers request data without a full page reload, why the old callback style was painful, and how fetch with async/await made it readable.
Tooling & quality
03 · entries-
A Practical Approach to JavaScript Testing
What to test, how the common kinds of tests differ, and how a modern test runner turns a vague intention to test into a fast feedback loop.
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Debugging JavaScript in the Browser
The browser devtools are a full debugger most developers barely use. Breakpoints, the call stack, watch expressions, and the network panel beat scattered logging.
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Utility Libraries vs. Modern JavaScript
General-purpose helper libraries once filled real gaps in the language. Many of those gaps have since closed. A guide to what to keep and what to drop.
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Common questions
Who is openjsan for?
Working developers who want a firmer grip on the parts of JavaScript that last: the language, the browser platform, and the tooling around a codebase. It is not an absolute-beginner course, but it does not assume you already know everything either.
Do I need to be an expert to read these articles?
No. The articles assume you can write some JavaScript and want to understand it more deeply. They skip the very basics and focus on the ideas that are commonly half-understood, with runnable examples throughout.
Are the browser tools really private?
Yes. Every tool runs as JavaScript in your own browser. Nothing you paste is sent to a server, logged, or stored, and the tools keep working with the tab offline once the page has loaded.
How often is new content published?
When an idea is worth writing down rather than on a fixed schedule. The aim is for each piece to stay useful for years, so quality and durability come before frequency.
Can I use the code examples in my own projects?
Yes. The snippets are written to illustrate a concept clearly and are meant to be adapted. Read them, understand what they do, and fit them to your own code rather than pasting blindly.
