argv_double

Usage

#include "stdlib/napi/argv_double.h"

stdlib_napi_argv_double( env, value, *out, *message, *err )

Converts a Node-API value to a double-precision floating-point number.

#include "stdlib/napi/argv_double.h"
#include <node_api.h>

static napi_value addon( napi_env env, napi_callback_info info ) {
    napi_value value;

    // ...

    double out;
    napi_value err;
    napi_status status = stdlib_napi_argv_double( env, value, &out, "Must be a number.", &err );
    assert( status == napi_ok );
    if ( err != NULL ) {
        assert( napi_throw( env, err ) == napi_ok );
        return NULL;
    }

    // ...
}

The function accepts the following arguments:

• env: [in] napi_env environment under which the function is invoked.
• value: [in] napi_value Node-API value.
• out: [out] double* destination for storing output value.
• message: [in] char* error message.
• err: [out] napi_value* pointer for storing a JavaScript error. If not provided a number, the function sets err with a JavaScript error; otherwise, err is set to NULL.

napi_status stdlib_napi_argv_double( const napi_env env, const napi_value value, double *out, const char *message, napi_value *err );

The function returns a napi_status status code indicating success or failure (returns napi_ok if success).

STDLIB_NAPI_ARGV_DOUBLE( env, name, argv, index )

Macro for converting an add-on callback argument to a double-precision floating-point number.

#include "stdlib/napi/argv_double.h"
#include "stdlib/napi/argv.h"
#include <node_api.h>

static double fcn( const double v ) {
    return v;
}

// ...

static napi_value addon( napi_env env, napi_callback_info info ) {
    // Retrieve add-on callback arguments:
    STDLIB_NAPI_ARGV( env, info, argv, argc, 1 );

    // Convert the first argument to a C type:
    STDLIB_NAPI_ARGV_DOUBLE( env, value, argv, 0 );

    // ...

    double out = fcn( value );
}

The macro expects the following arguments:

• env: environment under which the callback is invoked.
• name: output variable name.
• argv: name of the variable containing add-on callback arguments.
• index: argument index.