ffi.FFITypeOrString

enum FFIType

• bool = 11

  Boolean value

  Must be true or false. 0 and 1 type coercion is not supported.

  In C, this corresponds to:

  bool
  _Bool

• buffer = 20
• buffer_length = 21

  A TypedArray or DataView whose byte length is passed to the callee as an unsigned 64-bit integer. Pass the same view you passed for a buffer parameter; the engine reads pointer and length off the same object at call time, so the two always agree (an atomic snapshot -- unlike passing view.byteLength yourself). Engine-native only; not supported inside cc().

• char = 0
• cstring = 14

  When used as a returns, the value becomes a string (a NULL pointer becomes null).

  When used in args, it is equivalent to FFIType.pointer and additionally accepts a JavaScript string.

• double = 9

  IEEE-754 double precision float

• f32 = 10

  Alias of FFIType.float

• f64 = 9

  Alias of FFIType.double

• float = 10

  IEEE-754 single precision float

• function = 17
• i16 = 3

  16-bit signed integer

  Must be a value between -32768 and 32767

  When passing to an FFI function (C ABI), type coercion is not performed.

  In C:

  int16_t
  short // on arm64 & x64

  In JavaScript:

  var num = 0;

• i32 = 5

  32-bit signed integer

  Alias of FFIType.int32_t

• i64 = 7

  64-bit signed integer

  Alias of FFIType.int64_t

• i64_fast = 15

  Attempts to coerce a BigInt into a number when it fits. This improves performance, but the JavaScript value may be either a number or a BigInt, depending on the value.

  In C, this always becomes int64_t

• i8 = 1

  8-bit signed integer

  Must be a value between -128 and 127

  When passing to an FFI function (C ABI), type coercion is not performed.

  In C:

  signed char
  char // on x64 & aarch64 macOS

  In JavaScript:

  var num = 0;

• int = 5

  32-bit signed integer

  The same as int in C

  int

• int16_t = 3

  16-bit signed integer

  Must be a value between -32768 and 32767

  When passing to an FFI function (C ABI), type coercion is not performed.

  In C:

  int16_t
  short // on arm64 & x64

  In JavaScript:

  var num = 0;

• int32_t = 5

  32-bit signed integer

• int64_t = 7

  64-bit signed integer

• int8_t = 1

  8-bit signed integer

  Must be a value between -128 and 127

  When passing to an FFI function (C ABI), type coercion is not performed.

  In C:

  signed char
  char // on x64 & aarch64 macOS

  In JavaScript:

  var num = 0;

• napi_env = 18
• napi_value = 19
• pointer = 12

  Pointer value

  Alias of FFIType.ptr

• ptr = 12

  Pointer value

  See the ptr() function for getting a pointer from a TypedArray

  In C:

  void*

  In JavaScript:

  ptr(new Uint8Array(1))

• u16 = 4

  16-bit unsigned integer

  Must be a value between 0 and 65535, inclusive.

  When passing to an FFI function (C ABI), type coercion is not performed.

  In C:

  uint16_t
  unsigned short // on arm64 & x64

  In JavaScript:

  var num = 0;

• u32 = 6

  32-bit unsigned integer

  Alias of FFIType.uint32_t

• u64 = 8

  64-bit unsigned integer

• u64_fast = 16

  Attempts to coerce a BigInt into a number when it fits. This improves performance, but the JavaScript value may be either a number or a BigInt, depending on the value.

  In C, this always becomes uint64_t

• u8 = 2

  8-bit unsigned integer

  Must be a value between 0 and 255

  When passing to an FFI function (C ABI), type coercion is not performed.

  In C:

  unsigned char

  In JavaScript:

  var num = 0;

• uint16_t = 4

  16-bit unsigned integer

  Must be a value between 0 and 65535, inclusive.

  When passing to an FFI function (C ABI), type coercion is not performed.

  In C:

  uint16_t
  unsigned short // on arm64 & x64

  In JavaScript:

  var num = 0;

• uint32_t = 6

  32-bit unsigned integer

  The same as unsigned int in C (on x64 & arm64)

  C:

  unsigned int

  JavaScript:

  ptr(new Uint32Array(1))

• uint64_t = 8

  64-bit unsigned integer

• uint8_t = 2

  8-bit unsigned integer

  Must be a value between 0 and 255

  When passing to an FFI function (C ABI), type coercion is not performed.

  In C:

  unsigned char

  In JavaScript:

  var num = 0;

• void = 13

  void value

  void arguments are not supported

  void return type is the default return type

  In C:

  void