@watershedclimate/xlstream

xlstream

Memory-efficiently turns XLSX file into a transform stream with all its benefits.

• Stream is pausable.
• Emits all default events (data, end, etc.)
• Returns header, raw and formatted row data, as well as totalSheetSize and processedSheetSize (in bytes) in just one data event.
• Maintains desirable behavior of merged cells.
• Supports files created by OpenXML.
• Supports standard, Excel and custom number formats.

Installation

npm install xlstream

Example

source.xlsx contents:

A	B
hello	123

Where 123 is a 123.123 number formatted to be rounded to integer.

Script:

const { getXlsxStream } = require("xlstream");

(async () => {
  const stream = await getXlsxStream({
    filePath: "./source.xlsx",
    sheet: 0,
  });
  stream.on("data", (x) => console.log(x));
})();

Result:

{
    "raw": {
        "obj": { "A": "hello", "B": 123.123 },
        "arr": [ "hello", 123.123 ]
    },
    "formatted": {
        "obj": { "A": "hello", "B": 123 },
        "arr": [ "hello", 123 ]
    },
    "header": [],
    "totalSheetSize": 1110,
    "processedSheetSize": 1110
}

getXlsxStream

Returns transform stream of the sheet.

Options

option	type	description
filePath	string	Path to the XLSX file
sheet	string or number	If string is passed, finds sheet by it's name. If number, finds sheet by it's index.
withHeader	boolean or number	If true, column names will be taken from the first sheet row. If duplicated header name is found, column name will be prepended with column letter to maintain uniqueness. 0-based row location can be passed to this option if header is not located on the first row.
ignoreEmpty	boolean	If true, empty rows won't be emitted.
fillMergedCells	boolean	If true, merged cells will have the same value (by default, only the first cell of merged cells is filled with value). Warning! Enabling this feature may increase streaming time because file must be processed to detect merged cells before actual stream.
numberFormat	standard or excel or object	By default standard format is used. Excel implementation of number formatting differs from standard (can be read here) so excel option can be used to match this difference. If custom formatting is needed, a dictionary object can be passed to this option.
encoding	string	Sets file encoding.

getXlsxStreams

Async generator which yields transform streams of the sheets.

Options

Option	Type	Description
filePath	string	Path to the XLSX file
sheets	array of sheet objects	Options of sheet object can be found below.
encoding	string	Sets file encoding.

Sheet object

option	type	description
id	string or number	If string is passed, finds sheet by it's name. If number, finds sheet by it's index.
withHeader	boolean	If true, column names will be taken from the first sheet row. If duplicated header name is found, column name will be prepended with column letter to maintain uniqueness. 0-based row location can be passed to this option if header is not located on the first row.
ignoreEmpty	boolean	If true, empty rows won't be emitted.
fillMergedCells	boolean	If true, merged cells will have the same value (by default, only the first cell of merged cells is filled with value). Warning! Enabling this feature may increase streaming time because file must be processed to detect merged cells before actual stream.
numberFormat	standard or excel or object	By default standard format is used. Excel implementation of number formatting differs from standard (can be read here) so excel option can be used to match this difference. If custom formatting is needed, a dictionary object can be passed to this option.

getWorksheets

Returns array of sheets with name and hidden info.

Options

Option	Type	Description
filePath	string	Path to the XLSX file

Building

You can build js source by using npm run build command.

Testing

Tests can be run by using npm test command.