Examples

referencing
 and derefencing

var ref = require('ref')

// so we can all agree that a buffer with the int value written
// to it could be represented as an "int *"
var buf = new Buffer(4)
buf.writeInt32LE(12345, 0)

// first, what is the memory address of the buffer?
console.log(buf.hexAddress())  // ← '7FA89D006FD8'

// using `ref`, you can set the "type", and gain magic abilities!
buf.type = ref.types.int

// now we can dereference to get the "meaningful" value
console.log(buf.deref())  // ← 12345


// you can also get references to the original buffer if you need it.
// this buffer could be thought of as an "int **"
var one = buf.ref()

// and you can dereference all the way back down to an int
console.log(one.deref().deref())  // ← 12345


See the full API Docs for more examples.

The
 "type" interface

You can easily define your own "type" objects at attach to Buffer instances. It just needs to be a regular
 JavaScript Object that contains the following properties:



Name
Data Type
Description




size
Number
The size in bytes required to hold this type.


indirection
Number
The current level of indirection of the buffer. Usually this would be 1, and gets incremented on Buffers from ref() calls.
 A value of less than or equal to 0 is invalid.


get
Function (buffer, offset)
The function to invoke when dereferencing this type when the indirection level is 1.


set
Function (buffer, offset, value)
The function to invoke when setting a value to a buffer instance.


name
String
(optional) The name to use during debugging for this type.


alignment
Number
(optional) The alignment of this type when placed in a struct. Defaults to the type's size.




Be sure to check out the Wiki page of "Known Types", for the list of built-in ref types, as well as known external
 type implementations.

For example, you could define a "bigint" type that dereferences into a bigint instance:

var ref = require('ref')
var bigint = require('bigint')

// define the "type" instance according to the spec
var BigintType = {
    size: ref.sizeof.int64
  , indirection: 1
  , get: function (buffer, offset) {
      // return a bigint instance from the buffer
      return bigint.fromBuffer(buffer)
    }
  , set: function (buffer, offset, value) {
      // 'value' would be a bigint instance
      var val = value.toString()
      return ref.writeInt64(buffer, offset || 0, val)
    }
}

// now we can create instances of the type from existing buffers.
// "buf" is some Buffer instance returned from some external data
// source, which should contain "bigint" binary data.
buf.type = BigintType

// and now you can create "bigint" instances using this generic "types" API
var val = buf.deref()
            .add('1234')
            .sqrt()
            .shiftLeft(5)




ref *v0.3.3
Turn Buffer instances into "pointers"
What is ref?
ref is a native addon for Node.js that aids in doing C programming in JavaScript, by extending the built-in Buffer class with some fancy additions like:
Getting the memory address of a Buffer
Checking the endianness of the processor
Checking if a Buffer represents the NULL pointer
Reading and writing "pointers" with Buffers
Reading and writing C Strings (NULL-terminated)
Reading and writing JavaScript Object references
Reading and writing int64_t and uint64_t values
A "type" convention to define the contents of a Buffer
There is indeed a lot of meat to ref, but it all fits together in one way or another in the end.
For simplicity, ref's API can be broken down into 3 sections:
ref exports
All the static versions of ref's functions and default "types" available on the exports returned from require('ref').
"type" system
The "type" system allows you to define a "type" on any Buffer instance, and then use generic ref() and deref() functions to reference and dereference values.
Buffer extensions
Buffer.prototype gets extended with some convenience functions. These all just mirror their static counterpart, using the Buffer's this variable as the buffer variable.
ref exports
This section documents all the functions exported from require('ref').
ref.NULL ⇒ Buffer
A Buffer that references the C NULL pointer. That is, its memory address points to 0. Its length is 0 because accessing any data from this buffer would cause a segmentation fault.
console.log(ref.NULL);
<SlowBuffer@0x0 >
ref.NULL_POINTER ⇒ Buffer
NULL_POINTER is a pointer-sized Buffer instance pointing to NULL. Conceptually, it's equivalent to the following C code:
char *null_pointer;
null_pointer = NULL;
ref.address(Buffer buffer) → Number
buffer - The buffer to get the memory address of.
Return: The memory address the buffer instance.
Accepts a Buffer instance and returns the memory address of the buffer instance.
console.log(ref.address(new Buffer(1)));
4320233616

console.log(ref.address(ref.NULL)));
0
ref.alloc(Object|String type, ? value) → Buffer
type - The "type" object to allocate. Strings get coerced first.
value - (optional) The initial value set on the returned Buffer, using type's set() function.
Return: A new Buffer instance with it's type set to "type", and (optionally) "value" written to it.
Returns a new Buffer instance big enough to hold type, with the given value written to it.
var intBuf = ref.alloc(ref.types.int)
var int_with_4 = ref.alloc(ref.types.int, 4)
ref.allocCString(String string, String encoding) → Buffer
string - The JavaScript string to be converted to a C string.
encoding - (optional) The encoding to use for the C string. Defaults to 'utf8'.
Return: The new Buffer instance with the specified String wrtten to it, and a trailing NUL byte.
Returns a new Buffer instance with the given String written to it with the given encoding (defaults to 'utf8'). The buffer is 1 byte longer than the string itself, and is NUL terminated.
var buf = ref.allocCString('hello world');

console.log(buf.toString());
'hello world\u0000'
ref.coerceType(Object|String type) → Object
type - The "type" Object or String to coerce.
Return: A "type" object
Coerces a "type" object from a String or an actual "type" object. String values are looked up from the ref.types Object. So:
"int" gets coerced into ref.types.int.
"int *" gets translated into ref.refType(ref.types.int)
ref.types.int gets translated into ref.types.int (returns itself)
Throws an Error if no valid "type" object could be determined. Most ref functions use this function under the hood, so anywhere a "type" object is expected, a String may be passed as well, including simply setting the buffer.type property.
var type = ref.coerceType('int **');

console.log(type.indirection);
3
ref.deref(Buffer buffer) → ?
buffer - A Buffer instance to dereference.
Return: The returned value after dereferencing buffer.
Accepts a Buffer instance and attempts to "dereference" it. That is, first it checks the indirection count of buffer's "type", and if it's greater than 1 then it merely returns another Buffer, but with one level less indirection.
When buffer's indirection is at 1, then it checks for buffer.type which should be an Object with its own get() function.
var buf = ref.alloc('int', 6);

var val = ref.deref(buf);
console.log(val);
6
ref.derefType(Object|String type) → Object
type - The "type" object to create a dereference type from. Strings get coerced first.
Return: The new "type" object with its indirection decremented by 1.
Returns a new clone of the given "type" object, with its indirection level decremented by 1.
ref.endianness ⇒ String
A string that represents the native endianness of the machine's processor. The possible values are either "LE" or "BE".
console.log(ref.endianness);
'LE'
ref.get(Buffer buffer, Number offset, Object|String type) → ?
buffer - The Buffer instance to read from.
offset - (optional) The offset on the Buffer to start reading from. Defaults to 0.
type - (optional) The "type" object to use when reading. Defaults to calling getType() on the buffer.
Return: Whatever value the "type" used when reading returns.
Calls the get() function of the Buffer's current "type" (or the passed in type if present) at the given offset.
This function handles checking the "indirection" level and returning a proper "dereferenced" Bufffer instance when necessary.
ref.getType(Buffer buffer) → Object
buffer - The Buffer instance to get the "type" object from.
Return: The "type" object from the given Buffer.
Returns the "type" property of the given Buffer. Creates a default type for the buffer when none exists.
ref.isNull(Buffer buffer) → Boolean
buffer - The buffer to check for NULL.
Return: true or false.
Accepts a Buffer instance and returns true if the buffer represents the NULL pointer, false otherwise.
console.log(ref.isNull(new Buffer(1)));
false

console.log(ref.isNull(ref.NULL));
true
ref.readCString(Buffer buffer, Number offset) → String
buffer - The buffer to read a Buffer from.
offset - The offset to begin reading from.
Return: The String that was read from buffer.
Returns a JavaScript String read from buffer at the given offset. The C String is read until the first NULL byte, which indicates the end of the String.
This function can read beyond the length of a Buffer.
var buf = new Buffer('hello\0world\0');

var str = ref.readCString(buf, 0);
console.log(str);
'hello'
ref.readInt64BE(Buffer buffer, Number offset) → Number|String
buffer - The buffer to read a Buffer from.
offset - The offset to begin reading from.
Return: The Number or String that was read from buffer.
Returns a big-endian signed 64-bit int read from buffer at the given offset.
If the returned value will fit inside a JavaScript Number without losing precision, then a Number is returned, otherwise a String is returned.
var buf = ref.alloc('int64');
ref.writeInt64BE(buf, 0, '9223372036854775807');

var val = ref.readInt64BE(buf, 0)
console.log(val)
'9223372036854775807'
ref.readInt64LE(Buffer buffer, Number offset) → Number|String
buffer - The buffer to read a Buffer from.
offset - The offset to begin reading from.
Return: The Number or String that was read from buffer.
Returns a little-endian signed 64-bit int read from buffer at the given offset.
If the returned value will fit inside a JavaScript Number without losing precision, then a Number is returned, otherwise a String is returned.
var buf = ref.alloc('int64');
ref.writeInt64LE(buf, 0, '9223372036854775807');

var val = ref.readInt64LE(buf, 0)
console.log(val)
'9223372036854775807'
ref.readObject(Buffer buffer, Number offset) → Object
buffer - The buffer to read an Object from.
offset - The offset to begin reading from.
Return: The Object that was read from buffer.
Reads a JavaScript Object that has previously been written to the given buffer at the given offset.
var obj = { foo: 'bar' };
var buf = ref.alloc('Object', obj);

var obj2 = ref.readObject(buf, 0);
console.log(obj === obj2);
true
ref.readPointer(Buffer buffer, Number offset, Number length) → Buffer
buffer - The buffer to read a Buffer from.
offset - The offset to begin reading from.
length - (optional) The length of the returned Buffer. Defaults to 0.
Return: The Buffer instance that was read from buffer.
Reads a Buffer instance from the given buffer at the given offset. The size parameter specifies the length of the returned Buffer instance, which defaults to 0.
var buf = new Buffer('hello world');
var pointer = ref.alloc('pointer');

var buf2 = ref.readPointer(pointer, 0, buf.length);
console.log(buf.toString());
'hello world'
ref.readUInt64BE(Buffer buffer, Number offset) → Number|String
buffer - The buffer to read a Buffer from.
offset - The offset to begin reading from.
Return: The Number or String that was read from buffer.
Returns a big-endian unsigned 64-bit int read from buffer at the given offset.
If the returned value will fit inside a JavaScript Number without losing precision, then a Number is returned, otherwise a String is returned.
var buf = ref.alloc('uint64');
ref.writeUInt64BE(buf, 0, '18446744073709551615');

var val = ref.readUInt64BE(buf, 0)
console.log(val)
'18446744073709551615'
ref.readUInt64LE(Buffer buffer, Number offset) → Number|String
buffer - The buffer to read a Buffer from.
offset - The offset to begin reading from.
Return: The Number or String that was read from buffer.
Returns a little-endian unsigned 64-bit int read from buffer at the given offset.
If the returned value will fit inside a JavaScript Number without losing precision, then a Number is returned, otherwise a String is returned.
var buf = ref.alloc('uint64');
ref.writeUInt64LE(buf, 0, '18446744073709551615');

var val = ref.readUInt64LE(buf, 0)
console.log(val)
'18446744073709551615'
ref.ref(Buffer buffer) → Buffer
buffer - A Buffer instance to create a reference to.
Return: A new Buffer instance pointing to buffer.
ref() accepts a Buffer instance and returns a new Buffer instance that is "pointer" sized and has its data pointing to the given Buffer instance. Essentially the created Buffer is a "reference" to the original pointer, equivalent to the following C code:
char *buf = buffer;
char **ref = &buf;
ref.refType(Object|String type) → Object
type - The "type" object to create a reference type from. Strings get coerced first.
Return: The new "type" object with its indirection incremented by 1.
Returns a new clone of the given "type" object, with its indirection level incremented by 1.
Say you wanted to create a type representing a void *:
var voidPtrType = ref.refType(ref.types.void);
ref.reinterpret(Buffer buffer, Number size, Number offset) → Buffer
buffer - A Buffer instance to base the returned Buffer off of.
size - The length property of the returned Buffer.
offset - The offset of the Buffer to begin from.
Return: A new Buffer instance with the same memory address as buffer, and the requested size.
Returns a new Buffer instance with the specified size, with the same memory address as buffer.
This function "attaches" buffer to the returned Buffer to prevent it from being garbage collected.
ref.reinterpretUntilZeros(Buffer buffer, Number size, Number offset) → Buffer
buffer - A Buffer instance to base the returned Buffer off of.
size - The number of sequential, aligned NULL bytes are required to terminate the buffer.
offset - The offset of the Buffer to begin from.
Return: A new Buffer instance with the same memory address as buffer, and a variable length that is terminated by size NUL bytes.
Accepts a Buffer instance and a number of NULL bytes to read from the pointer. This function will scan past the boundary of the Buffer's length until it finds size number of aligned NULL bytes.
This is useful for finding the end of NUL-termintated array or C string. For example, the readCString() function could be implemented like:
function readCString (buf) {
  return ref.reinterpretUntilZeros(buf, 1).toString('utf8')
}
This function "attaches" buffer to the returned Buffer to prevent it from being garbage collected.
ref.set(Buffer buffer, Number offset, ? value, Object|String type)
buffer - The Buffer instance to write to.
offset - The offset on the Buffer to start writing to.
value - The value to write to the Buffer instance.
type - (optional) The "type" object to use when reading. Defaults to calling getType() on the buffer.
Calls the set() function of the Buffer's current "type" (or the passed in type if present) at the given offset.
This function handles checking the "indirection" level writing a pointer rather than calling the set() function if the indirection is greater than 1.
ref.writeCString(Buffer buffer, Number offset, String string, String encoding)
buffer - The Buffer instance to write to.
offset - The offset of the buffer to begin writing at.
string - The JavaScript String to write that will be written to the buffer.
encoding - (optional) The encoding to read the C string as. Defaults to 'utf8'.
Writes the given string as a C String (NULL terminated) to the given buffer at the given offset. "encoding" is optional and defaults to 'utf8'.
Unlike readCString(), this function requires the buffer to actually have the proper length.
ref.writeInt64BE(Buffer buffer, Number offset, Number|String input)
buffer - The buffer to write to.
offset - The offset to begin writing from.
input - This String or Number which gets written.
Writes the input Number or String as a big-endian signed 64-bit int into buffer at the given offset.
var buf = ref.alloc('int64');
ref.writeInt64BE(buf, 0, '9223372036854775807');
ref.writeInt64LE(Buffer buffer, Number offset, Number|String input)
buffer - The buffer to write to.
offset - The offset to begin writing from.
input - This String or Number which gets written.
Writes the input Number or String as a little-endian signed 64-bit int into buffer at the given offset.
var buf = ref.alloc('int64');
ref.writeInt64LE(buf, 0, '9223372036854775807');
ref.writeObject(Buffer buffer, Number offset, Object object)
buffer - A Buffer instance to write object to.
offset - The offset on the Buffer to start writing at.
object - The Object to be written into buffer.
Writes a pointer to object into buffer at the specified _offset.
This function "attaches" object to buffer to prevent it from being garbage collected.
var buf = ref.alloc('Object');
ref.writeObject(buf, 0, { foo: 'bar' });
ref.writePointer(Buffer buffer, Number offset, Buffer pointer)
buffer - A Buffer instance to write _pointer to.
offset - The offset on the Buffer to start writing at.
pointer - The Buffer instance whose memory address will be written to buffer.
Writes the memory address of pointer to buffer at the specified offset.
This function "attaches" object to buffer to prevent it from being garbage collected.
var someBuffer = new Buffer('whatever');
var buf = ref.alloc('pointer');
ref.writePointer(buf, 0, someBuffer);
ref.writeUInt64BE(Buffer buffer, Number offset, Number|String input)
buffer - The buffer to write to.
offset - The offset to begin writing from.
input - This String or Number which gets written.
Writes the input Number or String as a big-endian unsigned 64-bit int into buffer at the given offset.
var buf = ref.alloc('uint64');
ref.writeUInt64BE(buf, 0, '18446744073709551615');
ref.writeUInt64LE(Buffer buffer, Number offset, Number|String input)
buffer - The buffer to write to.
offset - The offset to begin writing from.
input - This String or Number which gets written.
Writes the input Number or String as a little-endian unsigned 64-bit int into buffer at the given offset.
var buf = ref.alloc('uint64');
ref.writeUInt64LE(buf, 0, '18446744073709551615');
ref._attach(Buffer buffer, Object|Buffer object)
buffer - A Buffer instance to attach object to.
object - An Object or Buffer to prevent from being garbage collected until buffer does.
Attaches object to buffer such that it prevents object from being garbage collected until buffer does.
ref._reinterpret(Buffer buffer, Number size, Number offset) → Buffer
buffer - A Buffer instance to base the returned Buffer off of.
size - The length property of the returned Buffer.
offset - The offset of the Buffer to begin from.
Return: A new Buffer instance with the same memory address as buffer, and the requested size.
Same as ref.reinterpret(), except that this version does not attach buffer to the returned Buffer, which is potentially unsafe if the garbage collector runs.
ref._reinterpretUntilZeros(Buffer buffer, Number size, Number offset) → Buffer
buffer - A Buffer instance to base the returned Buffer off of.
size - The number of sequential, aligned NULL bytes that are required to terminate the buffer.
offset - The offset of the Buffer to begin from.
Return: A new Buffer instance with the same memory address as buffer, and a variable length that is terminated by size NUL bytes.
Same as ref.reinterpretUntilZeros(), except that this version does not attach buffer to the returned Buffer, which is potentially unsafe if the garbage collector runs.
ref._writeObject(Buffer buffer, Number offset, Object object)
buffer - A Buffer instance to write object to.
offset - The offset on the Buffer to start writing at.
object - The Object to be written into buffer.
Same as ref.writeObject(), except that this version does not attach the Object to the Buffer, which is potentially unsafe if the garbage collector runs.
ref._writePointer(Buffer buffer, Number offset, Buffer pointer)
buffer - A Buffer instance to write _pointer to.
offset - The offset on the Buffer to start writing at.
pointer - The Buffer instance whose memory address will be written to buffer.
Same as ref.writePointer(), except that this version does not attach pointer to buffer, which is potentially unsafe if the garbage collector runs.
"type" system
A "type" in ref is simply an plain 'ol JavaScript Object, with a set of expected properties attached that implement the logic for getting & setting values on a given Buffer instance.
To attach a "type" to a Buffer instance, you simply attach the "type" object to the Buffer's type property. ref comes with a set of commonly used types which are described in this section.
Creating your own "type"
It's trivial to create your own "type" that reads and writes your own custom datatype/class to and from Buffer instances using ref's unified API.
To create your own "type", simply create a JavaScript Object with the following properties defined:
Name
Data
 Type
Description
size
Number
The
 size in bytes required to hold this datatype.
indirection
Number
The
 current level of indirection of the buffer. When defining your own "types", just set this value to 1.
get
Function
The
 function to invoke when ref.get() is
 invoked on a buffer of this type.
set
Function
The
 function to invoke when ref.set() is
 invoked on a buffer of this type.
name
String
(Optional) The
 name to use during debugging for this datatype.
alignment
Number
(Optional) The
 alignment of this datatype when placed inside a struct. Defaults to the type's size.
The built-in "types"
Here is the list of ref's built-in "type" Objects. All these built-in "types" can be found on the ref.types export Object. All the built-in types use "native endianness" when multi-byte datatypes are involved.
types.void
The void type.
types.int8
The int8 type.
types.uint8
The uint8 type.
types.int16
The int16 type.
types.uint16
The uint16 type.
types.int32
The int32 type.
types.uint32
The uint32 type.
types.int64
The int64 type.
types.uint64
The uint64 type.
types.float
The float type.
types.double
The double type.
types.Object
The Object type. This can be used to read/write regular JS Objects into raw memory.
types.CString
The CString (a.k.a "string") type.
CStrings are a kind of weird thing. We say it's sizeof(char *), and indirection level of 1, which means that we have to return a Buffer that is pointer sized, and points to a some utf8 string data, so we have to create a 2nd "in-between" buffer.
types.bool
The bool type.
Wrapper type around types.uint8 that accepts/returns true or false Boolean JavaScript values.
types.byte
The byte type.
types.char
The char type.
types.uchar
The uchar type.
types.short
The short type.
types.ushort
The ushort type.
types.int
The int type.
types.uint
The uint type.
types.long
The long type.
types.ulong
The ulong type.
types.longlong
The longlong type.
types.ulonglong
The ulonglong type.
types.size_t
The size_t type.
Buffer extensions
Buffer.prototype gets extended with some convenience functions that you can use in your modules and/or applications.
Buffer#address()
Shorthand for ref.address(this, …).
Accepts a Buffer instance and returns the memory address of the buffer instance.
console.log(ref.address(new Buffer(1)));
4320233616

console.log(ref.address(ref.NULL)));
0
Buffer#deref()
Shorthand for ref.deref(this, …).
Accepts a Buffer instance and attempts to "dereference" it. That is, first it checks the indirection count of buffer's "type", and if it's greater than 1 then it merely returns another Buffer, but with one level less indirection.
When buffer's indirection is at 1, then it checks for buffer.type which should be an Object with its own get() function.
var buf = ref.alloc('int', 6);

var val = ref.deref(buf);
console.log(val);
6
Buffer#hexAddress()
Shorthand for ref.hexAddress(this, …).
Buffer#inspect()
ref overwrites the default Buffer#inspect() function to include the hex-encoded memory address of the Buffer instance when invoked.
This is simply a nice-to-have.
Before:
console.log(new Buffer('ref'));
<Buffer 72 65 66>
After:
console.log(new Buffer('ref'));
<Buffer@0x103015490 72 65 66>
Buffer#isNull()
Shorthand for ref.isNull(this, …).
Accepts a Buffer instance and returns true if the buffer represents the NULL pointer, false otherwise.
console.log(ref.isNull(new Buffer(1)));
false

console.log(ref.isNull(ref.NULL));
true
Buffer#readCString()
Shorthand for ref.readCString(this, …).
Returns a JavaScript String read from buffer at the given offset. The C String is read until the first NULL byte, which indicates the end of the String.
This function can read beyond the length of a Buffer.
var buf = new Buffer('hello\0world\0');

var str = ref.readCString(buf, 0);
console.log(str);
'hello'
Buffer#readInt64BE()
Shorthand for ref.readInt64BE(this, …).
Returns a big-endian signed 64-bit int read from buffer at the given offset.
If the returned value will fit inside a JavaScript Number without losing precision, then a Number is returned, otherwise a String is returned.
var buf = ref.alloc('int64');
ref.writeInt64BE(buf, 0, '9223372036854775807');

var val = ref.readInt64BE(buf, 0)
console.log(val)
'9223372036854775807'
Buffer#readInt64LE()
Shorthand for ref.readInt64LE(this, …).
Returns a little-endian signed 64-bit int read from buffer at the given offset.
If the returned value will fit inside a JavaScript Number without losing precision, then a Number is returned, otherwise a String is returned.
var buf = ref.alloc('int64');
ref.writeInt64LE(buf, 0, '9223372036854775807');

var val = ref.readInt64LE(buf, 0)
console.log(val)
'9223372036854775807'
Buffer#readObject()
Shorthand for ref.readObject(this, …).
Reads a JavaScript Object that has previously been written to the given buffer at the given offset.
var obj = { foo: 'bar' };
var buf = ref.alloc('Object', obj);

var obj2 = ref.readObject(buf, 0);
console.log(obj === obj2);
true
Buffer#readPointer()
Shorthand for ref.readPointer(this, …).
Reads a Buffer instance from the given buffer at the given offset. The size parameter specifies the length of the returned Buffer instance, which defaults to 0.
var buf = new Buffer('hello world');
var pointer = ref.alloc('pointer');

var buf2 = ref.readPointer(pointer, 0, buf.length);
console.log(buf.toString());
'hello world'
Buffer#readUInt64BE()
Shorthand for ref.readUInt64BE(this, …).
Returns a big-endian unsigned 64-bit int read from buffer at the given offset.
If the returned value will fit inside a JavaScript Number without losing precision, then a Number is returned, otherwise a String is returned.
var buf = ref.alloc('uint64');
ref.writeUInt64BE(buf, 0, '18446744073709551615');

var val = ref.readUInt64BE(buf, 0)
console.log(val)
'18446744073709551615'
Buffer#readUInt64LE()
Shorthand for ref.readUInt64LE(this, …).
Returns a little-endian unsigned 64-bit int read from buffer at the given offset.
If the returned value will fit inside a JavaScript Number without losing precision, then a Number is returned, otherwise a String is returned.
var buf = ref.alloc('uint64');
ref.writeUInt64LE(buf, 0, '18446744073709551615');

var val = ref.readUInt64LE(buf, 0)
console.log(val)
'18446744073709551615'
Buffer#ref()
Shorthand for ref.ref(this, …).
ref() accepts a Buffer instance and returns a new Buffer instance that is "pointer" sized and has its data pointing to the given Buffer instance. Essentially the created Buffer is a "reference" to the original pointer, equivalent to the following C code:
char *buf = buffer;
char **ref = &buf;
Buffer#reinterpret()
Shorthand for ref.reinterpret(this, …).
Returns a new Buffer instance with the specified size, with the same memory address as buffer.
This function "attaches" buffer to the returned Buffer to prevent it from being garbage collected.
Buffer#reinterpretUntilZeros()
Shorthand for ref.reinterpretUntilZeros(this, …).
Accepts a Buffer instance and a number of NULL bytes to read from the pointer. This function will scan past the boundary of the Buffer's length until it finds size number of aligned NULL bytes.
This is useful for finding the end of NUL-termintated array or C string. For example, the readCString() function could be implemented like:
function readCString (buf) {
  return ref.reinterpretUntilZeros(buf, 1).toString('utf8')
}
This function "attaches" buffer to the returned Buffer to prevent it from being garbage collected.
Buffer#writeCString()
Shorthand for ref.writeCString(this, …).
Writes the given string as a C String (NULL terminated) to the given buffer at the given offset. "encoding" is optional and defaults to 'utf8'.
Unlike readCString(), this function requires the buffer to actually have the proper length.
Buffer#writeInt64BE()
Shorthand for ref.writeInt64BE(this, …).
Writes the input Number or String as a big-endian signed 64-bit int into buffer at the given offset.
var buf = ref.alloc('int64');
ref.writeInt64BE(buf, 0, '9223372036854775807');
Buffer#writeInt64LE()
Shorthand for ref.writeInt64LE(this, …).
Writes the input Number or String as a little-endian signed 64-bit int into buffer at the given offset.
var buf = ref.alloc('int64');
ref.writeInt64LE(buf, 0, '9223372036854775807');
Buffer#writeObject()
Shorthand for ref.writeObject(this, …).
Writes a pointer to object into buffer at the specified _offset.
This function "attaches" object to buffer to prevent it from being garbage collected.
var buf = ref.alloc('Object');
ref.writeObject(buf, 0, { foo: 'bar' });
Buffer#writePointer()
Shorthand for ref.writePointer(this, …).
Writes the memory address of pointer to buffer at the specified offset.
This function "attaches" object to buffer to prevent it from being garbage collected.
var someBuffer = new Buffer('whatever');
var buf = ref.alloc('pointer');
ref.writePointer(buf, 0, someBuffer);
Buffer#writeUInt64BE()
Shorthand for ref.writeUInt64BE(this, …).
Writes the input Number or String as a big-endian unsigned 64-bit int into buffer at the given offset.
var buf = ref.alloc('uint64');
ref.writeUInt64BE(buf, 0, '18446744073709551615');
Buffer#writeUInt64LE()
Shorthand for ref.writeUInt64LE(this, …).
Writes the input Number or String as a little-endian unsigned 64-bit int into buffer at the given offset.
var buf = ref.alloc('uint64');
ref.writeUInt64LE(buf, 0, '18446744073709551615');
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REF参数的说明一般是这样的:
  ref 在使用过程中会改变变量的值,且例子如下:
  public static void ValueParam(string str)
  {
   str = "251";
  }
  public static void RefParam(ref string str)
  {
   str = "250";
  }
  public static void Main()
  {
   string str = "249";
   ValueParam(str);
   Console.WriteLine(" Value Param:"+str);
    RefParam(ref str);
   Console.WriteLine(" Ref Param:"+str);
}
结果为:
Value Param:249
Ref Param:250 

在react开发过程中，有时会碰到一些需求需要我们去操控dom，那么我们就可以给组件挂载一个ref属性，然后就可以通过ref调用这个组件的方法或者属性之类的。
接下来我们就来看看函数组件和类组件都是如何去挂载创建ref和使用它的：

函数式组件(Hook)：
// 首先引入React及useRef
import React, { useRef } from 'react;
function Content() {
	// 创建ref
	const fileInputEl = useRef(null);
	return (
		<>
			{/* 在你的元素或者组件上面挂载ref */}
			<input ref={fileInputEl} type={'file'} hidden />
			{/* 使用ref */}
			{/* 当点击这个div的时候触发input的点击事件 */}
			<div onClick={() => fileInputEl.current.click()}>上传文件</div>
		</>
	)
}


类组件创建使用ref
// 引入React
import React, { Component } from 'react';
export default class Content extends Component {
	constructor(props) {
		super(props);
		// 通过React.createRef()创建ref,挂载到组件上
		this.editTableEl = React.createRef();
	}
	componentWillReceiveProps() {
		// 当走入componentWillReceiveProps生命周期时会触发此ref挂载到的组件的refreshDataSource()方法（PS：这个方法是自己在挂载ref的那个组件中定义的）
		this.editTableEl.current && this.editTableEl.current.refreshDataSource();
	}
	render() {
		return (
			<div>
				<EditableTable
					// 挂载ref
					ref={this.editTableEl}
				/>
			</div>
		)
	}
}

如果consoe.log（this.$refs.wrapper）打印出来的是undefined，那么就页面多刷新几次，
因为ref不是响应式的

注意event.currentTarget.refs弹出的是undefined，因为refs只对this起作用

注意：在vue的项目中尽量不要用DOM去操作元素，不然在渲染页面的时候会出问题（尤其是通过数据和索引之间的值来控制页面切换的时候），尽量用this.$refs.wrapper去操作。