# expressionContainsObservableCall

Canonical page: https://www.adaptabletools.com/docs/reference/expressioncontainsobservablecall

True when the expression text contains an observable brace call
(`CHANGE_COUNT{[price], WITHIN(5m)}`, `PREVIOUS{[c]}`, `ROW_AGE{}`, …) at
any depth. The dual-name paren spelling `PERCENT_CHANGE([c])` is a
data-change scalar, not an observable call. Clock reads (`NOW()`) are not
observable calls either — callers that need "live" use the compiled
dependencies. Empty or unparseable text → false.

```ts title="TypeScript"
expressionContainsObservableCall: (expression: string | undefined | null, options?: InferExpressionKindOptions) => boolean
```