2nd/10_Wiki/Topic_JavaScript/JavaScript_BigInt.md

---
id: javascript-bigint
title: "JavaScript BigInt"
category: "Frontend"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["BigInt", "arbitrary precision integer", "n suffix", "BigInt()", "ES2020 integers", "large integers"]
duplicate_of: ""
source_trust_level: "B"
confidence_score: 0.89
created_at: 2026-06-23
updated_at: 2026-06-23
review_reason: ""
merge_history: []
tags: ["javascript", "js", "web", "frontend", "w3schools", "bigint", "number", "es2020"]
raw_sources: ["https://www.w3schools.com/js/js_bigint.asp"]
applied_in: []
github_commit: ""
---

# [[JavaScript BigInt]]

## 🎯 한 줄 통찰 (One-line insight)
`BigInt` is a JavaScript data type for whole numbers too large for the ordinary `Number` type — it represents integers of arbitrary size (limited only by memory), but cannot hold decimals and cannot be freely mixed with `Number` values. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Purpose** — `BigInt` handles integers larger than the safe-integer limits of the `Number` type, representing integers of any size constrained only by available memory. [S1]
- **Why it exists** — JavaScript Numbers are 64-bit floating point (IEEE 754) and only accurate up to 15 digits; safe integers run from `9007199254740991` (`2⁵³ − 1`) down to `-9007199254740991`. [S1]
- **Two creation forms** — an integer literal with an `n` suffix, or the `BigInt()` constructor (from a string or a Number). [S1]
- **It is a distinct type** — `typeof` a BigInt is `"bigint"`; it is the third numeric-family data type, making eight JavaScript types in total. [S1]
- **No mixing without conversion** — arithmetic between a BigInt and a Number throws a `TypeError`; convert explicitly with `Number()` or `BigInt()`. [S1]
- **No decimals** — a BigInt cannot have decimal values. [S1]
- **ES2020 feature** — supported in modern browsers since September 2020. [S1]

## 🧩 추출된 패턴 (Extracted patterns)
- **`n` literal vs constructor** — `999999999999999n` (literal) or `BigInt("999999999999999")` (string constructor avoids the 15-digit accuracy loss). [S1]
- **Explicit cross-type conversion** — to combine with a Number, wrap one side: `Number(x) + y`. [S1]
- **Loose vs strict equality** — `10n == 10` is `true`, but `10n === 10` is `false` because the types differ. [S1]
- **No `>>>` on BigInt** — unsigned right shift is not allowed with BigInts. [S1]

## 📖 세부 내용 (Details)
**What is JavaScript BigInt?** — `BigInt` is a data type that can represent integers of any size, limited only by available memory. [S1]

**JavaScript Accuracy / Numbers are 64-bits Floating Point** — JavaScript Numbers are only accurate up to 15 digits and use 64-bit floating-point format (IEEE 754). The safe integer range is `9007199254740991` (`2⁵³ − 1`) to `-9007199254740991` (`−(2⁵³ − 1)`). [S1]
```javascript
// 15 digits:
let x = 999999999999999;

// 16 digits:
let y = 9999999999999999;
```
```javascript
// MAX = 9007199254740991
let x = Number.MAX_SAFE_INTEGER;

// MIN = -9007199254740991
let y = Number.MIN_SAFE_INTEGER;
```
```javascript
// Max (accurate)
let x = 9007199254740991;

// Max + 10 (inaccurate)
let y = x + 10;
```

**How to Create a BigInt** — use an integer literal with an `n` suffix, or the `BigInt()` constructor: [S1]
```javascript
// Using an integer literal with an n suffix:
let x = 999999999999999n;

// Using the BigInt() constructor with a string:
let y = BigInt("999999999999999");
```

**BigInt is a JavaScript Datatype** — `typeof` returns `"bigint"`: [S1]
```javascript
let x = BigInt(999999999999999);

let type = typeof x;
```
BigInt is the third numeric data type. The eight JavaScript data types are: String, Number, Bigint, Boolean, Undefined, Null, Symbol, Object. [S1]

**Arithmetic Operators** — BigInt supports `+`, `-`, `++`, `--`, `*`, `/`, `%`, `**`: [S1]
```javascript
let x = 9007199254740995n;
let y = 9007199254740995n;

let z = x * y;
```

**Mixing BigInt and Numbers** — mixing throws a `TypeError`; convert explicitly: [S1]
```javascript
let x = 10n;
let y = 5;

let z = x + y; // ❌ TypeError
```
```javascript
let x = 10n;
let y = 5;

let z = Number(x) + y;
```

**BigInt / Number Conversions** — BigInt to Number with `Number(value)`, Number to BigInt with `BigInt(value)`; large conversions may result in Infinity or precision loss. [S1]

**BigInt Decimals** — a BigInt cannot have decimals, and mixing with division throws an error: [S1]
```javascript
let x = 5n;
let y = x / 2;
// ❌ Error: Cannot mix BigInt and other types, use explicit conversion.
```

**Comparison Operators** — BigInt supports `<`, `>`, `==`, `===`, `!==`, `<=`, `>=`. Strict equality between a BigInt and a Number is always false: [S1]
```javascript
// true
let x = (10n > 5n);

// false (different types)
let y = (10n === 10);

// true (loose equality)
let z = (10n == 10);
```

**Bitwise Operators** — BigInt supports `&`, `|`, `^`, `~`: [S1]
```javascript
let a = 5n; // 0101
let b = 3n; // 0011

let x = (a & b); // 1n (0001)
let y = (a | b); // 7n (0111)
let z = (a ^ b); // 6n (0110)
let n = (~a);    // -6n
```

**Bitwise Shift Operators** — BigInt supports `<<` and `>>`. Unsigned right shift (`>>>`) is not allowed with BigInts: [S1]
```javascript
let big = 10n; // binary: 1010

let x = (big << 2n); // 40n (101000)
let y = (big >> 1n); // 5n (0101)
```

**BigInt Hex, Octal and Binary** [S1]
```javascript
let num = 256n;
let oct = 0o400n;
let hex = 0x100n;
let bin = 0b100000000n;
```

**Precision Curiosity** — Number rounding makes two distinct large integers compare equal, while BigInt keeps them distinct: [S1]
```javascript
9007199254740992 === 9007199254740993; // is true !!!
```
```javascript
9007199254740992n === 9007199254740993n; // is false !!!
```

**Summary** — BigInt enables arbitrary-precision integer arithmetic. Limitations: no decimal support, incompatibility with `Math` functions, and `JSON.stringify()` cannot handle BigInts. [S1]

**Browser Support** — BigInt is an ES2020 feature, fully supported in modern browsers since September 2020. [S1]

## 🛠️ 적용 사례 (Applied in summary)
The page's own snippets are the canonical applied examples — creating BigInts via the `n` literal and the `BigInt()` constructor, multiplying large values, the explicit `Number(x) + y` conversion, and the precision-comparison curiosity. No external project/commit applications found in the source.

## 💻 코드 패턴 (Code patterns)
Create a BigInt (language: JavaScript):
```javascript
let a = 999999999999999n;
let b = BigInt("999999999999999");
```
Mix safely with a Number via explicit conversion:
```javascript
let x = 10n;
let y = 5;
let z = Number(x) + y;
```
Compare with loose vs strict equality:
```javascript
10n == 10;   // true
10n === 10;  // false
```

## ⚖️ 비교 및 선택 기준 (Comparison & decision criteria)
- **Use `Number`** for everyday math and any value within the safe-integer range (`±9007199254740991`) or requiring decimals. [S1]
- **Use `BigInt`** when integers exceed the safe-integer range and must stay exact (the page cites cryptography, IDs, and timestamps), accepting that decimals, `Math` functions, and `JSON.stringify()` are unavailable. [S1]
- **Never mix the two directly** — arithmetic across the types throws a `TypeError`; convert one side explicitly. [S1]

## ⚖️ 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:** 0.89
- **중복 검사 결과:** 신규 생성 (New discovery)

## 🔗 지식 그래프 (Knowledge Graph)
- **상위/루트:** [[JavaScript Tutorial]]
- **관련 개념:** [[JavaScript Numbers]], [[JavaScript Number Properties]], [[JavaScript Bitwise]], [[JavaScript Data Types]]
- **참조 맥락:** Referenced when exact large-integer arithmetic is required beyond the Number safe-integer limit.

## 📚 출처 (Sources)
- [S1] W3Schools — JavaScript BigInt — https://www.w3schools.com/js/js_bigint.asp

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