2nd/10_Wiki/Topic_JavaScript/JavaScript_JSON_Objects.md

---
id: json-objects
title: "JSON Objects"
category: "Frontend"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["JSON objects", "JSON object literal", "access JSON object", "loop JSON object", "JSON dot bracket notation"]
duplicate_of: ""
source_trust_level: "B"
confidence_score: 0.88
created_at: 2026-06-23
updated_at: 2026-06-23
review_reason: ""
merge_history: []
tags: ["javascript", "js", "web", "frontend", "w3schools", "json", "objects"]
raw_sources: ["https://www.w3schools.com/js/js_json_objects.asp"]
applied_in: []
github_commit: ""
---

# [[JSON Objects]]

## 🎯 한 줄 통찰 (One-line insight)
A JSON object literal is curly-brace text of key/value pairs; once parsed into a JavaScript object you read its members by dot or bracket notation and iterate them with a for-in loop — but the literal itself is a string format, not "a JSON object." [S1]

## 🧠 핵심 개념 (Core concepts)
- **JSON object literals are surrounded by curly braces `{}`** and contain key/value pairs. [S1]
- **Keys and values rules** — keys must be strings, and values must be a valid JSON data type. [S1]
- **Terminology caution** — it is a common mistake to call a JSON object literal "a JSON object." JSON cannot be an object; JSON is a string format. [S1]
- **Two ways to obtain an object** — write a JavaScript object directly from a literal, or parse a JSON string with `JSON.parse()`. [S1]
- **Two ways to access members** — dot notation (`myObj.name`) or bracket notation (`myObj["name"]`). [S1]
- **Iterate with for-in** — loop over keys, and access each value via `myObj[x]`. [S1]

## 🧩 추출된 패턴 (Extracted patterns)
- **Literal → object** — `myObj = {...}` or `myObj = JSON.parse(myJSON)`. [S1]
- **Dot vs bracket access** — `myObj.name` equals `myObj["name"]`. [S1]
- **For-in over keys** — `for (const x in myObj)` yields keys; index with `myObj[x]` for values. [S1]

## 📖 세부 내용 (Details)
**JSON object literals**
JSON object literals are surrounded by curly braces `{}`. JSON object literals contains key/value pairs. Keys must be strings, and values must be a valid JSON data type. It is a common mistake to call a JSON object literal "a JSON object." JSON cannot be an object. JSON is a string format. [S1]

This is a JSON string: [S1]
```json
{"name":"John", "age":30, "car":null}
```

**Creating a JavaScript object**
You can create a JavaScript object directly from a JSON object literal: [S1]
```javascript
myObj = {"name":"John", "age":30, "car":null};
```
Normally you create a JavaScript object by parsing a JSON string: [S1]
```javascript
myObj = JSON.parse(myJSON);
```

**Accessing object values**
You can access object values by using dot (`.`) notation: [S1]
```javascript
x = myObj.name;
```
You can also access object values by using bracket (`[]`) notation: [S1]
```javascript
x = myObj["name"];
```

**Looping an object**
You can loop through object properties with a for-in loop. Loop printing the keys: [S1]
```javascript
const myJSON = '{"name":"John", "age":30, "car":null}';
const myObj = JSON.parse(myJSON);

let text = "";
for (const x in myObj) {
  text += x + ", ";
}
```
In a for-in loop, use the bracket notation to access the values: [S1]
```javascript
const myJSON = '{"name":"John", "age":30, "car":null}';
const myObj = JSON.parse(myJSON);

let text = "";
for (const x in myObj) {
  text += myObj[x] + ", ";
}
```

## 🛠️ 적용 사례 (Applied in summary)
Applied examples on the page: build `myObj` from a literal and from `JSON.parse()`; read values via dot and bracket notation; and iterate with for-in (keys, then values via `myObj[x]`). No external project/commit applications found in the source.

## 💻 코드 패턴 (Code patterns)
Parse then access:
```javascript
const myObj = JSON.parse('{"name":"John", "age":30, "car":null}');
x = myObj.name;       // dot notation
x = myObj["name"];    // bracket notation
```
Iterate values:
```javascript
let text = "";
for (const x in myObj) {
  text += myObj[x] + ", ";
}
```

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
No contradictions found in the source.

## ✅ 검증 상태 및 신뢰도
- **상태:** draft
- **검증 단계:** conceptual (실제 적용 사례 발견 시 applied/validated로 승격 가능)
- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
- **신뢰 점수:** 0.88
- **중복 검사 결과:** 신규 생성 (New discovery)

## 🔗 지식 그래프 (Knowledge Graph)
- **상위/루트:** [[JavaScript Tutorial]]
- **관련 개념:** [[JavaScript JSON Arrays]], [[JavaScript JSON Parse]], [[JavaScript JSON Data Types]], [[JavaScript JSON Syntax]]
- **참조 맥락:** Referenced whenever reading or iterating the members of a parsed JSON object.

## 📚 출처 (Sources)
- [S1] W3Schools — JSON Objects — https://www.w3schools.com/js/js_json_objects.asp

## 📝 변경 이력 (Change history)
- 2026-06-23: Initial draft synthesized from the W3Schools "JSON Objects" page (Astra wiki-curation, P-Reinforce v3.1 format).