Number Number Object
Last updated: 2026-09-09
Number Number Object
Number is JavaScript's built-in number object providing formatting, type checks and safe range constants. All JS numbers are IEEE 754 doubles.
| Category | Numbers |
|---|---|
| ES version | ES1 |
📝 Syntax
const n = 42;
Number.isInteger(n); // true
n.toFixed(2); // '42.00'
Number.MAX_SAFE_INTEGER;▶ Example
Edit the code, press Run, and see the result in the output panel:
Output：
19.99
true
42
3.14⚠️ Warning JS has only one number type (IEEE 754 double) — no integer type. 0.1 + 0.2 !== 0.3.
💡 Tip For money, work in integer cents to avoid floating-point errors.
🏷️ Related Items
💡 Related Cases
More case studies coming soon — check back later.
📚 Related Tutorials
❓ FAQ
QDoes JS have an integer type?
ANo — all numbers are doubles. Integers are just floats without decimals.
QWhy is 0.1 + 0.2 !== 0.3?
AFloating-point precision — binary can't represent some decimals exactly.
QparseInt vs parseFloat?
AparseInt parses integer prefix; parseFloat parses float prefix.
