Math.random() Random number
Last updated: 2026-09-09
Math.random() Random number
Math.random returns a pseudo-random decimal in [0, 1).
| Category | Math |
|---|---|
| ES version | ES1 |
📝 Syntax
Math.random();Returns：A random decimal between 0 (inclusive) and 1 (exclusive).
Mutates the original：No (returns a new value)
▶ Example
Edit the code, press Run, and see the result in the output panel:
Output：
0.8396451821434205
0
6💡 Tip Random integer: Math.floor(Math.random() * (max - min + 1)) + min.
⚠️ Warning Not cryptographically secure — use crypto.getRandomValues for security.
🌐 Browser support
| Browser |  Chrome |
 Edge |
 Firefox |
 Safari |
 Opera |
|---|---|---|---|---|---|
| Math.random() | ✓ v1 | ✓ v12 | ✓ v1 | ✓ v1 | ✓ v1 |
| Supported by all modern browsers | |||||
🏷️ Related Items
💡 Related Cases
More case studies coming soon — check back later.
📚 Related Tutorials
❓ FAQ
QHow to generate random int in range?
AMath.floor(Math.random() * (max - min + 1)) + min.
QCan Math.random return 1?
ANo — range is [0, 1), exclusive of 1.
QNeed secure random?
AUse crypto.getRandomValues(new Uint32Array(1)).
