CSVWriter

Writes rows to a CSV file, one array of values per row.

export.js

const writer = datasource.csv("exports/actuals.csv");

writer.write(["year", "month", "product", "amount"]);
writer.write(["2026", "Jan", "Widgets", 1200.5]);
writer.write(["2026", "Jan", "Gadgets", 830]);

writer.close();

actuals.csv

"year","month","product","amount"
"2026","Jan","Widgets",1200.5
"2026","Jan","Gadgets",830

Constructor

datasource.csv datasource.csv(fileName) CSVWriter | null

Creates a CSV file in the filesystem and returns a CSVWriter, or null when the path is invalid. If the file already exists, it's replaced.

Parameter	Type	Description
fileName	string	The path of the file, for example "exports/actuals.csv". Missing folders are created.

// A file in the exports folder
const writer = datasource.csv("exports/actuals.csv");

// A file in a folder that doesn't exist yet; the folder is created
const writer = datasource.csv("exports/2026/actuals.csv");

Overview

• One row per call: pass write() an array of values, one per column.
• How values are written: numbers and booleans are written bare, null is written as NULL, and everything else is written as quoted text.
• Format: rows are comma-delimited, text is wrapped in double quotes, and rows are separated by a Windows-style line break (\r\n). Change these with the setter methods before writing any rows.
• Always close: call close() when you've finished, so everything is written to the file.

Methods

write write(values) boolean

Writes one row to the file. Returns true on success, or false when the file is closed or values isn't an array.

Parameter	Type	Description
values	array	The values for one row, in column order.

close close()

Writes any buffered rows to the file and closes it. Always call it when you've finished writing: until then, the file may not be complete. Writes after close() are ignored and logged as errors.

setDelimiter setDelimiter(delimiter)

Sets the text written between values. The default is a comma. Call it before writing any rows.

Parameter	Type	Description
delimiter	string	The delimiter, for example ";", or "\t" for tab.

getDelimiter getDelimiter() string

Returns the text written between values, "," unless changed with setDelimiter().

setQuoteCharacter setQuoteCharacter(quoteCharacter)

Sets the character wrapped around text values. The default is a double quote. Call it before writing any rows.

Parameter	Type	Description
quoteCharacter	string	The quote character. Pass "" to turn quoting off.

getQuoteCharacter getQuoteCharacter() string

Returns the character wrapped around text values, " unless changed with setQuoteCharacter().

setLineBreak setLineBreak(lineBreak)

Sets the text written between rows. The default is "\r\n". Call it before writing any rows.

Parameter	Type	Description
lineBreak	string	The line break, for example "\n" for Unix-style line endings.

getLineBreak getLineBreak() string

Returns the text written between rows, "\r\n" unless changed with setLineBreak().

Examples

A semicolon-delimited file

export.js

const writer = datasource.csv("exports/budget.csv");
writer.setDelimiter(";");

writer.write(["account", "month", "amount"]);
writer.write(["4000", "Jan", 1000]);
writer.write(["4000", "Feb", 1100]);

writer.close();

budget.csv

"account";"month";"amount"
"4000";"Jan";1000
"4000";"Feb";1100

Values without quotes

export.js

const writer = datasource.csv("exports/products.csv");
writer.setQuoteCharacter("");

writer.write(["code", "name", "active"]);
writer.write(["W-01", "Widget", true]);
writer.write(["G-02", "Gadget", false]);

writer.close();

products.csv

code,name,active
W-01,Widget,true
G-02,Gadget,false

Related

• CSVReader: reads CSV files.