@posprint/command-builder

ESC/POS TSC Buffer Builder

JavaScript library that implements the ESC/POS and TSC protocol to buffer, also provides an AST like JSON tree structure that you can preparing convertible templates (hmtl/xml) as you want.

Features

• ESC/POS and TSC protocol compatible
• Root, text, table, tr, td, img, blank, separator and qrcode nodes include style attribues implementation
• Command node for cashbox and cut paper implementation
• Compile semantic nodes to raw buffer according to ESC/POS and TSC protocol

Usage

1. Installation of nodejs environment

  npm install @posprint/command-builder

The library is distributed as umd package, just import to your front-end project the normally.

2. Build json tree to command buffer

Build ESC command buffer from json tree

const { buildCommand } = require('@posprint/command-builder')

const jsonTree = {
  "elementName": "root",
  "attributes":{},
  "children": [{
    "elementName": "blank",
    "attributes":{},
    "children": null
  },
  {
    "elementName": "text",
    "attributes": {
      "font-size": "wide-high",
      "align": "center"
    },
    "children": "Change Table"
  }]
}

const cmd = await buildCommand(jsonTree, { type: 'esc', encoding: 'UTF-8', paperSize: [80]})

const buffer =  commands.getBuffer().flush() 

After json tree is built by command bulder, pass buffer to printer tcp socket directly for printing.

Build TSC command buffer from json tree

const { buildCommand } = require('@posprint/command-builder')

{
  "elementName": "root",
  "attributes":{},
  "children": [
  {
    "elementName": "text",
    "attributes":
    {
      "align": "center"
    },
    "children": "---Order List---"
  },
  {
    "elementName": "text",
    "attributes":{},
    "children": "Latte"
  },
  {
    "elementName": "text",
    "attributes":
    {},
    "children": "Take out"
  },
  {
    "elementName": "separator",
    "attributes":
    {},
    "children": null
  },
  {
    "elementName": "text",
    "attributes":
    {},
    "children": "05-18 14:29 #498"
  },
  ]
}

const cmd = await buildCommand(jsonTree, { type: 'tsc', encoding: 'UTF-8', paperSize: [40, 30]})

const buffer =  commands.getBuffer().flush()

Tsc only supports text, separator and root right now, other nodes will be ignored when you printer type is TSC. We are extending more tsc nodes, for example table, img, blank.

3. Send raw buffer to printer through tcp connection

View example folder to get demo and screenshot how to buffer be printed by physical printer.

API

buildCommand

buildCommand(json, option)

• json: json tree structure of nodes, view node tree description below
• object.type: string type allows 'esc' and 'tsc', default value is 'esc'
• object.encoding: string type of encoding, default value is 'UTF-8'
• object.paperSize: array type of printer paper size, 'tsc' type contains two elements, default value is [80]. ie, [80], [58], [40, 30]

Returns a Template instance which can invoke getBuffer() method to get raw buffer.

validateNode

validateNode(json, option)

• json, option parameters are the same as buildCommand, the difference is json tree not be built buffer in order to validate json tree of nodes

Node Json Tree

Json tree that contains multiple nodes must have a root node, each node contains elementName, attributes, children and other attributes.

The specific json tree format is as follows:

  {
    "elementName": "root",
    "attributes": {},
    "children": [{
        "elementName": "blank",
        "attributes": {},
        "children": null
      },
      {
        "elementName": "text",
        "attributes":
        {
          "align": "center"
        },
        "children": "Order List"
      }
    ]
  }

node specification

Attribute	Type	Requirement	specification
elementName	string	required	A node describes a type of printing instruction, text, picture, QR code, etc. Allowed element name see supported nodes below.
attributes	object	optional	Describe the style of the node, font, style, alignment, etc.
children	array, string, null	optional	The content printed by printer or the child node.

You can use different json parser to convert the HTML/XML or other source file into a json tree.

Supported Nodes

• root
• text
• command
• blank
• img
• qrcode
• separator
• table
• tr
• td
• section

Exmaples

View source code in the exmaples folder about ESC and TSC content printing.

Recommended HTML/XML Parser

1. Live demo of parsers look here
2. React temple parser supports all nodes of current library is available here