From 922a8b5c54d0842e5fc63b8c18d3a589efcfe0bc Mon Sep 17 00:00:00 2001 From: darkless456 Date: Wed, 13 Aug 2025 15:59:39 +0000 Subject: [PATCH] chore: update study note to 0bcd26b2841ebab121500fb912c52b5297238d8c --- blog/2025-08-13-interview-tips-2025-8.md | 30 ++++++++++++------------ 1 file changed, 15 insertions(+), 15 deletions(-) diff --git a/blog/2025-08-13-interview-tips-2025-8.md b/blog/2025-08-13-interview-tips-2025-8.md index d3272fb..1c3d832 100644 --- a/blog/2025-08-13-interview-tips-2025-8.md +++ b/blog/2025-08-13-interview-tips-2025-8.md @@ -8,41 +8,41 @@ hide_table_of_contents: false ## JavaScript Core 1) What is a closure? -- A closure is a function that remembers its outer scope via the **lexical environment**, even after the outer function returns. -- If asked: It keeps access to variables where it was created. Example: `function outer(){ let x=1; return function(){ console.log(x) } }`. +- A closure is a function that remembers its outer scope via the **lexical environment（词法环境）**, even after the outer function returns. +- If asked: It keeps access to variables where it was created. 2) Hoisting in JavaScript? - **Declarations** are moved to the top; **var** hoists with undefined, **let/const** hoist but stay in **TDZ**. -- If asked: `var` is usable before line but is `undefined`. `let/const` throw if used before declared. Example: `console.log(a); var a=1;` vs `console.log(b); let b=1;`. +- If asked: `var` is usable before line but is `undefined`. `let/const` throw if used before declared. 3) How does “this” work? -- **this** depends on **call site**: default, **method**, **call/apply/bind**, **new**, or **arrow** (lexical). +- **this** depends on **call site（调用点）**: default, **method**, **call/apply/bind**, **new**, or **arrow** (lexical). -- If asked: In a method, `this` is the object. With `call/apply/bind`, you set it. Arrow uses the outer `this`. Example: `obj.fn()` vs `fn.call(obj)`. +- If asked: In a method, `this` is the object. With `call/apply/bind`, you set it. Arrow uses the outer `this`. 4) Prototype vs class? - **Prototype chain** is native inheritance; **class** is syntax sugar over prototypes. -- If asked: `class` makes prototype code look cleaner. Under the hood it still uses prototypes. Example: `class A{}` ≈ function + `A.prototype`. +- If asked: `class` makes prototype code look cleaner. Under the hood it still uses prototypes. 5) Event loop basics? - JS is **single-threaded**; **event loop** runs **call stack**, then **microtasks** (Promises), then **macrotasks**. - If asked: Promises run before timers in the same tick. Example order: sync → microtasks → timers. 6) Promise vs async/await? -- **Promises** model async; **async/await** is syntax for **sequential** style with **try/catch**. -- If asked: `await` pauses inside async function. Use `try/catch` for errors. Example: `const x = await fetch()`. +- **Promises** model async; **async/await** is syntax for **sequential（顺序的）** style with **try/catch**. +- If asked: `await` pauses inside async function. Use `try/catch` for errors. 7) Debounce vs throttle? -- **Debounce** waits for silence; **Throttle** limits calls to a **rate**. +- **Debounce（延迟）** waits for silence; **Throttle（节流）** limits calls to a **rate**. - If asked: Debounce: run after user stops typing. Throttle: run at most once per 100ms while scrolling. 8) == vs ===? -- **===** checks **type + value**; **==** does **coercion** (avoid unless sure). +- **===（Strict Equality）** checks **type + value**; **==（Loose Equality）** does **implicit type conversion**. - If asked: `0 == false` is true; `0 === false` is false. Prefer `===` to avoid surprises. 9) var vs let vs const? - **var** is **function-scoped**; **let/const** are **block-scoped**; **const** blocks **reassignment**. -- If asked: Use `const` by default, `let` when you reassign, avoid `var`. Blocks are `{ ... }`. +- If asked: Use `const` by default, `let` when you reassign, avoid `var`. 10) Arrow function differences? - **Arrow** has **lexical this**, no **arguments**, not **constructible**. @@ -62,7 +62,7 @@ hide_table_of_contents: false 14) Immutable data—why? - **Immutability** reduces **side effects**, helps **debugging**/**change detection**. -- If asked: Don’t modify input. Return new arrays/objects. Example: `const b = a.map(x=>x)`. +- If asked: Don’t modify input. Return new arrays/objects. 15) Module systems: CommonJS vs ES Modules? - **CommonJS** is **sync** (Node legacy); **ESM** is **static**, supports **tree-shaking**. @@ -180,7 +180,7 @@ hide_table_of_contents: false - If asked: Use workers for CPU heavy tasks (hashing). Use cluster to use many CPU cores for HTTP. 43) child_process use cases? -- Run **shell commands**, **spawn** tools, offload work; manage **stdout/stderr**/**exit codes**. +- Run **shell commands**, **spawn（衍生）** tools, offload work; manage **stdout/stderr**/**exit codes**. - If asked: Example: `exec('ls -la', cb)`; `spawn` for streaming output. 44) Express middleware order? @@ -192,7 +192,7 @@ hide_table_of_contents: false - If asked: Keep `.env` out of git. In cloud, use managed secret stores. 46) Logging best practices? -- **Structured logs** (JSON), **correlation IDs**, **levels**, avoid **PII**. +- **Structured logs** (JSON), **correlation（相关性） IDs**, **levels**, avoid **PII**. - If asked: Include `requestId` in each log line to trace a request. 47) Securing a Node API? @@ -221,7 +221,7 @@ hide_table_of_contents: false - **Mock**: behavior + **assertions**; **stub**: **canned** responses; **spy**: **record** calls. - If asked: Use a mock when the test must fail if a function wasn’t called. -53) Test Pyramid? +53) Test Pyramid（金字塔）? - More **unit**, fewer **integration**, few **e2e** for **speed**/**stability**. - If asked: UI tests are slow and flaky; keep them minimal but meaningful.