hubcap evalframe
Evaluate JavaScript in a specific frame.
When to use
Use evalframe to run a JavaScript expression inside a particular iframe or frame context. Use frames to list available frame IDs first. Use eval when you need to evaluate JavaScript in the main frame only.
Usage
hubcap evalframe <frame-id> <expression>Arguments
| Argument | Type | Required | Description |
|---|---|---|---|
frame-id | string | Yes | Target frame identifier (use frames to list available IDs) |
expression | string | Yes | JavaScript expression to evaluate |
Flags
None.
Output
| Field | Type | Description |
|---|---|---|
frameId | string | The frame in which the expression was evaluated |
type | string | JavaScript type of the result (e.g. string, number, boolean, object) |
value | any | The returned value |
{"frameId":"frame-123","type":"number","value":42}Errors
| Condition | Exit code | Stderr |
|---|---|---|
| JavaScript evaluation error | 1 | error: JS exception: <message> |
| Invalid frame ID | 1 | error: creating isolated world: ... |
| Chrome not connected | 2 | error: connecting to Chrome: ... |
| Timeout | 3 | error: timeout |
Examples
Evaluate in a specific frame:
hubcap evalframe 'frame-123' 'document.title'Get the body text of a frame:
hubcap evalframe 'frame-123' 'document.body.innerText'Check the URL loaded in a frame:
hubcap evalframe 'frame-123' 'window.location.href'List frames then evaluate in the first one:
hubcap frames | jq -r '.[0].id' | xargs -I{} hubcap evalframe '{}' 'document.title'