# PDL_GetJSParamDouble

## Description

Returns a parameter passed in a JavaScript invocation of a registered Plug-in handler function when the parameter is expected to be a `double`.

Handler functions serve as interfaces between a JavaScript app and a Plug-in app. See "JavaScript and Plug-in Interface" for more information on how this works.

## Syntax

>     double PDL_GetJSParamDouble(PDL_JSParameters *params, int paramNum);

Argument | Description
--- | ---
params | Parameters from which to extract data. This is passed to the handler function and should simply be passed on here. This type's internals are hidden from the user.
paramNum | Number of parameter to extract (0 to n-1).

## Returns

>     double parameter, or 0.0 if parameter does not exist.

See also:

- PDL_RegisterJSHandler
- PDL_JSRegistrationComplete
- PDL_GetNumJSParams
- PDL_GetJSParamString
- PDL_GetJSParamInt
- PDL_JSException
- PDL_JSReply
- PDL_CallJS