= += -= 等赋值运算符 Assignment operators
Last updated: 2026-09-09
= += -= 等赋值运算符 Assignment operators
Assignment operators store values in variables. Compound assignments combine an operation with assignment.
| Category | Operators |
|---|---|
| ES version | ES1 |
📝 Syntax
let x = 5; x += 3; // x = x + 3Returns：The assigned value.
Mutates the original：No (returns a new value)
▶ Example
Edit the code, press Run, and see the result in the output panel:
Output：
2💡 Tip += is the standard counter increment: count += 1.
ℹ️ info Logical assignment operators (??=, ||=, &&=) are ES2021.
🌐 Browser support
| Browser |  Chrome |
 Edge |
 Firefox |
 Safari |
 Opera |
|---|---|---|---|---|---|
| = += -= 等赋值运算符 | ✓ v1 | ✓ v12 | ✓ v1 | ✓ v1 | ✓ v1 |
| Supported by all modern browsers | |||||
🏷️ Related Operators
💡 Related Cases
More case studies coming soon — check back later.
📚 Related Tutorials
❓ FAQ
Q= vs ==?
A= assigns; == compares. Use === for conditions.
Q+= vs ++?
A+= n adds n; ++ adds 1 only.
QWhat is ??=?
ANull coalescing assignment — only assigns when null/undefined.
