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Software: explore STEM content (page 7 of 25) · openstem

All fields Software Mathematics Physics Chemistry Biology Engineering Astronomy Environmental Other Software Software groups

Explore STEM Content

Search the community's STEM library — free to study, yours to make your own.

Software

Programming, algorithms and systems on openstem — flashcards, notes, quizzes, sketches and flowcharts shared by the community. Study free, or clone anything into your library.

Content Groups1

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Collection4 items

01CSS Layout

02HTML & Semantics

03Software · L1 · HTML & CSS: How the Browser Renders a Page

+1 more

Software

Software · L1 · HTML & CSS

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Software · L1 · HTML & CSS

Flashcards10 cards

What are the six phases of the Node.js event loop in order?1 / 10

timers → pending callbacks → idle/prepare → poll → check → close callbacks. Microtasks (process.nextTick, then Promises) are drained between every phase transition.

Software

Performance & Diagnostics

@openstem

Performance & Diagnostics

Quiz6 questions

Which property defines a one-way function f?

Af is hard to compute but easy to invertBf is efficiently computable, but no PPT adversary can find a preimage of f(x) for random x except with negligible probabilityCf is a bijection with an efficiently computable inverseDf is a random oracle

Software

Software · L5 · Cryptographic Foundations

@openstem

Software · L5 · Cryptographic Foundations

Flowchart15 objects

Software

Software · L2 · HTML & CSS: Computing an Element's Accessible Name · flowchart

@openstem

Software · L2 · HTML & CSS: Computing an Element's Accessible Name · flowchart

Quiz5 questions

What is the main benefit of embedding related data as a subdocument?

AOne read retrieves the parent and its related data togetherBIt removes the 16MB document size limitCIt always uses less disk spaceDIt avoids needing an _id field

Software

Software · L1 · MongoDB: Schema Design — Embedding vs Referencing

@openstem

Software · L1 · MongoDB: Schema Design — Embedding vs Referencing

Quiz5 questions

What does `[1, 2, 3].map(x => x * 2)` return?

A`[1, 2, 3]`, unchangedBA new array `[2, 4, 6]`C`undefined`DThe number 6

Software

Software · L1 · JavaScript: Fundamentals Check

@openstem

Software · L1 · JavaScript: Fundamentals Check

Note~189 words · 1 min

Threads: Running Code Concurrently A Thread is an independent path of execution within a program. Java can run many threads at once (on multi-core hardware, truly in parallel), letting one program do several things without blocking. You sta

Software

Software · L2 · Java: Concurrency Basics

@openstem

Software · L2 · Java: Concurrency Basics

Flashcards10 cards

What is the difference between streaming replication and logical replication in PostgreSQL?1 / 10

Streaming replication ships WAL bytes, producing a byte-for-byte copy of the primary (physical). Logical replication decodes WAL into row-change events and applies them, enabling selective table replication, cross-version, or cross-OS replication.

Software

Replication & Scaling

@openstem

Replication & Scaling

Flowchart19 objects

Software

Software · L1 · JavaScript: Array Method Choices · flowchart

@openstem

Software · L1 · JavaScript: Array Method Choices · flowchart

Flashcards10 cards

What is a closure in JavaScript?1 / 10

A closure is a function that remembers the variables from its enclosing lexical scope, even after that scope has finished executing. Every function in JS is a closure.

Software

Closures & Scope

@openstem

Closures & Scope

Flashcards10 cards

What is the difference between continuous delivery and continuous deployment?1 / 10

Continuous delivery keeps every change deployable and releases on a manual approval, while continuous deployment automatically ships every passing change to production with no manual gate.

Software

CI/CD Pipelines

@openstem

CI/CD Pipelines

Flowchart15 objects

Software

Software · L1 · Design Patterns: Choosing a Creational Pattern · flowchart

@openstem

Software · L1 · Design Patterns: Choosing a Creational Pattern · flowchart

Flashcards10 cards

What does the `?` suffix on a type like `String?` mean in Dart?1 / 10

It marks the type as nullable, allowing the value to be either a String or null. A bare `String` is non-nullable and can never hold null under sound null safety.

Software

Null Safety

@openstem

Null Safety

Flashcards10 cards

What information does EXPLAIN ANALYZE give that plain EXPLAIN does not?1 / 10

EXPLAIN ANALYZE actually executes the query and reports actual rows returned, actual time per node, and loop counts, compared to EXPLAIN's estimate-only plan.

Software

Performance Tuning

@openstem

Performance Tuning

Flowchart9 objects

Software

Software · L1 · Flutter: Styling & Theming · flowchart

@openstem

Software · L1 · Flutter: Styling & Theming · flowchart

Flashcards10 cards

What method is at the core of the `Future` trait?1 / 10

`poll(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output>`. The executor repeatedly calls `poll`; it returns `Poll::Pending` (registering a waker) or `Poll::Ready(output)` when complete.

Software

Async Internals, Pin & Variance

@openstem

Async Internals, Pin & Variance

Flashcards10 cards

What is the test pyramid?1 / 10

A guideline for test distribution: many fast, cheap unit tests at the base, fewer integration tests in the middle, and few slow, brittle end-to-end tests at the top. It optimizes for fast feedback and maintainability.

Software

Test Types

@openstem

Test Types

Flashcards10 cards

What sits at the top of the GCP resource hierarchy?1 / 10

The Organization node is the root of the hierarchy, representing a company. Below it are Folders, then Projects, then resources. Policies set higher up are inherited downward.

Software

Cloud Fundamentals

@openstem

Cloud Fundamentals

Flashcards10 cards

What kind of database is Amazon RDS?1 / 10

RDS is a managed relational database service supporting engines like PostgreSQL, MySQL, MariaDB, Oracle, and SQL Server, handling patching, backups, and failover.

Software

Databases (RDS & DynamoDB)

@openstem

Databases (RDS & DynamoDB)

Note~93 words · 1 min

The Critical Rendering Path A browser doesn't just 'show' a page — it builds up several internal trees, one step feeding the next, before anything appears on screen. A `<script>` tag without `defer` or `async` blocks HTML parsing entirely w

Software

Software · L1 · HTML & CSS: How the Browser Renders a Page

@openstem

Software · L1 · HTML & CSS: How the Browser Renders a Page

Quiz5 questions

In the OAuth authorization code flow, what does the client exchange for an access token?

AThe user's raw passwordBA short-lived authorization code, plus its client secret or PKCE verifierCThe refresh token onlyDNothing — access tokens are issued immediately on redirect

Software

Software · L2 · Networking & HTTP: Auth & Protocols Check

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Software · L2 · Networking & HTTP: Auth & Protocols Check

Flashcards10 cards

What are the primitive types in TypeScript?1 / 10

`string`, `number`, `bigint`, `boolean`, `symbol`, `null`, and `undefined`. These map directly to JavaScript primitives. TypeScript also adds `never`, `unknown`, `any`, and `void` as special types.

Software

Everyday Types

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Everyday Types

Flashcards10 cards

What is the difference between `json` and `jsonb` in PostgreSQL?1 / 10

`json` stores the exact text and reparses on access; `jsonb` stores a decomposed binary form that is faster to query and indexable.

Software

Data Types & JSONB

@openstem

Data Types & JSONB

Flashcards9 cards

What does it mean for an HTTP method to be idempotent?1 / 9

Calling it once or many times with the same request produces the same server state as calling it once. GET, PUT, DELETE, HEAD, and OPTIONS are idempotent; POST is not.

Software

API Design & REST

@openstem

API Design & REST

Note~141 words · 1 min

What Is a Transaction? A transaction wraps one or more statements so they succeed or fail together. `BEGIN` starts it, `COMMIT` makes every change permanent, and `ROLLBACK` undoes everything as if none of it happened. This matters whenever

Software

Software · L1 · SQL: Transactions & ACID

@openstem

Software · L1 · SQL: Transactions & ACID

Note~739 words · 4 min

Relational Algebra as SQL's Semantics Codd's relational model (1970) represents data as relations — mathematically, subsets of a Cartesian product of attribute domains, i.e. sets of tuples. Relational algebra is the procedural counterpart:

Software

Software · L5 · Database Theory: Relational Algebra, Serializability, and Query Optimization

@openstem

Software · L5 · Database Theory: Relational Algebra, Serializability, and Query Optimization

Quiz5 questions

Which traversal is the natural choice for shortest path in an unweighted graph?

ABFSBDFSCIn-order traversalDBinary search

Software

Software · L2 · Data Structures & Algos: Graph Traversal

@openstem

Software · L2 · Data Structures & Algos: Graph Traversal

Collection4 items

01Caching Strategies

02Software · L3 · Caching Strategies

03Software · L3 · Choosing a Caching Strategy

+1 more

Software

Software · L3 · Caching Strategies

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Software · L3 · Caching Strategies

Collection4 items

01Software · L5 · Programming Language Semantics

02Software · L5 · Programming Language Semantics

03Software · L5 · Semantics Styles and Type Soundness

+1 more

Software

Software · L5 · Programming Language Semantics

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Software · L5 · Programming Language Semantics

Note~140 words · 1 min

Four Built-ins, Four Jobs Python's built-in collections overlap in what they can hold but differ sharply in what they guarantee. Picking the wrong one doesn't usually cause a crash — it just makes the code fight against behavior it doesn't

Software

Software · L1 · Python: Choosing the Right Collection

@openstem

Software · L1 · Python: Choosing the Right Collection

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