The JavaScript Questions Repository is a comprehensive collection of JavaScript interview questions designed to test knowledge across various JavaScript concepts. This repository serves as both an educational resource for developers looking to enhance their JavaScript skills and as a preparation tool for technical interviews. It features a structured set of multiple-choice questions with detailed explanations, organized into multiple language translations to make the content accessible to a global audience.
This repository contains a curated set of JavaScript questions covering topics from basic language syntax to advanced concepts such as asynchronous programming, closures, and prototypal inheritance. Each question includes:
The questions are primarily designed to test understanding of JavaScript nuances, edge cases, and common pitfalls that developers encounter.
Sources: README.md3-18 nl-NL/README.md1-13
The repository is organized into a main README.md file containing the original English questions, with separate directories for each language translation. Each translation follows a similar structure to maintain consistency across languages.
Sources: README.md22-50 nl-NL/README.md16-44 id-ID/README.md16-43 zh-TW/README_zh-TW.md16-21
Each question follows a consistent format to provide a clear learning experience. The questions are numbered sequentially and include code snippets, multiple options, and detailed explanations.
Example question structure from the repository:
###### 1. What's the output?
```javascript
function sayHi() {
console.log(name);
console.log(age);
var name = 'Lydia';
let age = 21;
}
sayHi();
Lydia and undefinedLydia and ReferenceErrorReferenceError and 21undefined and ReferenceError#### Answer: D
Within the function, we first declare the name variable with the var keyword. This means that the variable gets hoisted (memory space is set up during the creation phase) with the default value of undefined, until we actually get to the line where we define the variable. We haven't defined the variable yet on the line where we try to log the name variable, so it still holds the value of undefined.
Variables with the let keyword (and const) are hoisted, but unlike var, don't get initialized. They are not accessible before the line we declare (initialize) them. This is called the "temporal dead zone". When we try to access the variables before they are declared, JavaScript throws a ReferenceError.
Sources: README.md54-82 nl-NL/README.md48-76 id-ID/README.md47-73 zh-TW/README_zh-TW.md24-52 zh-CN/README-zh_CN.md12-40
The repository covers a wide range of JavaScript concepts, carefully selected to provide comprehensive coverage of the language's features and common challenges. The following table shows the main concept categories with examples of specific topics:
| Category | Specific Concepts |
|---|---|
| Variables & Scope | Hoisting, Temporal dead zone, Block scope vs Function scope, var/let/const differences |
| Functions | Regular functions, Arrow functions, this context, Closures, Function parameters, IIFEs |
| Objects & Prototypes | Object creation, Property access, Prototypal inheritance, Object methods, Constructor functions |
| Asynchronous JavaScript | Event loop, setTimeout/setInterval, Promises, Async/await, Callbacks |
| Type Coercion | Implicit/explicit conversion, Truthy/falsy values, Equality operators (== vs ===) |
| ES6+ Features | Template literals, Destructuring, Spread syntax, Rest parameters, Modules |
| DOM & Events | Event propagation, Event bubbling, Event capturing, Event listeners |
| Data Structures | Arrays, Sets, Maps, TypedArrays, Array methods |
Sources: README.md54-1500 nl-NL/README.md76-1000 id-ID/README.md73-800 zh-TW/README_zh-TW.md100-1000
The repository contains a diverse range of questions, from basic to advanced, covering various JavaScript concepts. Here are some examples of the types of questions included:
Variable scoping and hoisting:
Event loop and asynchronous behavior:
Object references and mutation:
Type coercion and operators:
Sources: README.md54-166 nl-NL/README.md48-168 id-ID/README.md47-165 zh-TW/README_zh-TW.md24-144
The repository provides translations in over 20 languages, making the content accessible to developers worldwide. Each translation is maintained in its own directory with a consistent file naming convention.
| Language | Directory | README File |
|---|---|---|
| English (Original) | root | README.md |
| Arabic | ar-AR | README_AR.md |
| Bosnian | bs-BS | README-bs_BS.md |
| Chinese (Simplified) | zh-CN | README-zh_CN.md |
| Chinese (Traditional) | zh-TW | README_zh-TW.md |
| Dutch | nl-NL | README.md |
| French | fr-FR | README_fr-FR.md |
| German | de-DE | README.md |
| Indonesian | id-ID | README.md |
| Japanese | ja-JA | README-ja_JA.md |
| Korean | ko-KR | README-ko_KR.md |
| Portuguese (Brazil) | pt-BR | README_pt_BR.md |
| Romanian | ro-RO | README.ro.md |
| Russian | ru-RU | README.md |
| Spanish | es-ES | README-ES.md |
| Thai | th-TH | README-th_TH.md |
| Turkish | tr-TR | README-tr_TR.md |
| Vietnamese | vi-VI | README-vi.md |
Sources: README.md22-50 nl-NL/README.md16-44 id-ID/README.md16-43 zh-TW/README_zh-TW.md16-21
The repository is designed to be an interactive learning resource. Each question challenges the reader to think about JavaScript behavior before revealing the answer. This design encourages active learning and helps reinforce JavaScript concepts.
The repository can be used as:
Sources: README.md11-18 nl-NL/README.md7-12 id-ID/README.md5-10 zh-TW/README_zh-TW.md6-11
The repository welcomes contributions from the community, particularly for:
Contributors should follow the existing question format and ensure translations accurately capture both the technical content and the nuances of each explanation.
Sources: README.md14-20 zh-TW/README_zh-TW.md20-21
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