?. 可选链 Optional chaining
Last updated: 2026-09-09
?. 可选链 Optional chaining
Optional chaining ?. safely accesses nested properties — returns undefined instead of throwing.
| Category | Operators |
|---|---|
| ES version | ES2020 |
📝 Syntax
obj?.prop?.subPropReturns：The property value or undefined.
Mutates the original：No (returns a new value)
▶ Example
Edit the code, press Run, and see the result in the output panel:
Output：
Beijing
undefined
undefined💡 Tip ?. replaces verbose && chains — shorter and clearer.
ℹ️ info ?.() for safe method calls; ?.[] for safe key access.
🌐 Browser support
| Browser |  Chrome |
 Edge |
 Firefox |
 Safari |
 Opera |
|---|---|---|---|---|---|
| ?. 可选链 | ✓ v80 | ✓ v80 | ✓ v72 | ✓ v13.1 | ✓ v67 |
| Supported by all modern browsers | |||||
🏷️ Related Operators
💡 Related Cases
More case studies coming soon — check back later.
📚 Related Tutorials
❓ FAQ
Q?. vs && chain?
A?. is shorter and less error-prone than && chains.
QCan ?. be used for assignment?
ANo — ?. is read-only. Use ??= or conditionals.
QWhen was ?. added?
AES2020.
