String.includes() Does it contain a substring
Last updated: 2026-09-09
String.includes() Does it contain a substring
includes checks whether the string contains the given substring, returning true or false.
| Category | Strings |
|---|---|
| ES version | ES2015 |
📝 Syntax
const found = str.includes(substring, position);⚙️ Parameters
| substring | The substring to search for, case-sensitive. |
|---|---|
| position | Optional. Search start position, default 0. |
Returns：A boolean.
Mutates the original：No (returns a new value)
▶ Example
Edit the code, press Run, and see the result in the output panel:
Output：
true
false
true💡 Tip toLowerCase() before searching is the standard case-insensitive check.
ℹ️ info includes with empty string is always true.
🌐 Browser support
| Browser |  Chrome |
 Edge |
 Firefox |
 Safari |
 Opera |
|---|---|---|---|---|---|
| String.includes() | ✓ v41 | ✓ v12 | ✓ v40 | ✓ v9 | ✓ v28 |
| Supported by all modern browsers | |||||
🏷️ Related Items
💡 Related Cases
More case studies coming soon — check back later.
📚 Related Tutorials
❓ FAQ
Qincludes or indexOf?
Aincludes for existence; indexOf when you need the position.
QIs includes case-sensitive?
AYes. Case-insensitive: str.toLowerCase().includes(keyword.toLowerCase()).
QDoes includes support regex?
ANo — use str.match or /pattern/.test(str).
