buffer.md

ZJS API for Buffer

• Introduction
• Web IDL
• API Documentation
• Sample Apps

Introduction

Buffer is a [node.js API] (https://nodejs.org/dist/latest-v6.x/docs/api/buffer.html) to read and write binary data accurately from JavaScript. ZJS supports a minimal subset of this API that will be expanded as the need arises.

Web IDL

This IDL provides an overview of the interface; see below for documentation of specific API functions.

// Buffer is a global object constructor that is always available

[Constructor(unsigned long length)]
interface Buffer {
    unsigned char readUInt8(unsigned long offset);
    void writeUInt8(unsigned char value, unsigned long offset);
    unsigned short readUInt16BE(unsigned long offset);
    void writeUInt16BE(unsigned short value, unsigned long offset);
    unsigned short readUInt16LE(unsigned long offset);
    void writeUInt16LE(unsigned short value, unsigned long offset);
    unsigned long readUInt32BE(unsigned long offset);
    void writeUInt32BE(unsigned long value, unsigned long offset);
    unsigned long readUInt32LE(unsigned long offset);
    void writeUInt32LE(unsigned long value, unsigned long offset);
    string toString(string encoding);
    readonly attribute unsigned long length;
};

API Documentation

Buffer constructor

Buffer(unsigned long length);

The length argument specifies the length in bytes of the Buffer object.

Buffer.readUInt family

unsigned char readUInt8(unsigned long offset);
unsigned short readUInt16BE(unsigned long offset);
unsigned short readUInt16LE(unsigned long offset);
unsigned long readUInt32BE(unsigned long offset);
unsigned long readUInt32LE(unsigned long offset);

The offset should be provided but will be treated as 0 if not given. Returns the value of the short or long located at the given offset. If the offset is outside the bounds of the Buffer, returns an error.

The BE or LE refers to whether the bytes will be read in big-endian (highest byte first) or little-endian (lowest byte first) order.

Buffer.writeUInt family

void writeUInt8(unsigned char value, unsigned long offset);
void writeUInt16BE(unsigned short value, unsigned long offset);
void writeUInt16LE(unsigned short value, unsigned long offset);
void writeUInt32BE(unsigned long value, unsigned long offset);
void writeUInt32LE(unsigned long value, unsigned long offset);

The offset should be provided but will be treated as 0 if not given. Writes value to the buffer starting at the given offset. If the target area goes outside the bounds of the Buffer, returns an error.

The BE or LE refers to whether the value will be written in big-endian (highest byte first) or little-endian (lowest byte first) order.

Buffer.toString

string toString(string encoding);

Currently, the only supported encoding is 'hex'. If 'hex' is given, returns the contents of the Buffer encoded in hexadecimal digits. Otherwises, returns an error.

Sample Apps

• Buffer sample
• WebBluetooth Demo