JavaScript Includes
includes() checks whether a string contains a given substring and returns a boolean. True or false. The search is case-sensitive. It is the clean, readable replacement for the old indexOf(...) !== -1 idiom.
Syntax
str.includes(search)Examples
| Input | Arguments | Output |
|---|---|---|
| "hello world" | "world" | true |
| "hello" | "H" | false |
| ↳ Case-sensitive: "H" ≠ "h". | ||
When to use it
- Filter a list by keyword.
- Guard logic on the presence of a marker or flag in text.
Gotchas
- Case-sensitive. Lowercase both sides first for a case-insensitive check.
Try it live
Type your input and see Includes transform it instantly.
Want to go further? Chain Includes with other functions, pipe one output into the next and watch your data transform in the visual Playground.