toml

TOML Parser for Node.js

If you haven't heard of TOML, well you're just missing out. Go check it out now. Back? Good.

TOML Spec Support

toml-node supports TOML v1.1.0, scoring 673/680 (99.0%) on the official toml-test compliance suite:

	Pass	Total	Rate
Valid tests	213	214	99.5%
Invalid tests	460	466	98.7%
Total	673	680	99.0%

The 7 remaining failures are inherent JavaScript platform limitations shared by all JS TOML parsers:

• 1 valid test: 64-bit integer precision (Number can't represent values beyond Number.MAX_SAFE_INTEGER)
• 6 invalid tests: UTF-8 encoding validation (Node.js handles UTF-8 decoding at the engine level before the parser sees the data)

Feature Support

• Strings: basic, literal, multiline, all escape sequences (\uXXXX, \UXXXXXXXX, \xHH, \e)
• Integers: decimal, hexadecimal (0xDEADBEEF), octal (0o755), binary (0b11010110)
• Floats: decimal, scientific notation, inf, -inf, nan
• Booleans: true, false
• Dates/Times: offset date-time, local date-time, local date, local time; seconds optional
• Arrays: mixed types allowed
• Tables: standard, inline (with dotted/quoted keys, newlines, trailing commas), array of tables
• Keys: bare, quoted, dotted (fruit.apple.color = "red")
• Comments: # line comments

Installation

npm install toml

Requires Node.js 20 or later. Zero runtime dependencies.

Usage

const toml = require('toml');
const data = toml.parse(someTomlString);

toml.parse throws an exception on parse errors with line and column properties:

try {
  toml.parse(someBadToml);
} catch (e) {
  console.error(`Parsing error on line ${e.line}, column ${e.column}: ${e.message}`);
}

Nesting Depth Limit

To guard against stack overflow on maliciously deep input, arrays and inline tables may nest at most 500 levels deep by default; input past the limit throws a normal parse error. Adjust the limit with the maxDepth option:

toml.parse(someTomlString, { maxDepth: 100 });

Date/Time Values

Offset date-times are returned as JavaScript Date objects. Local date-times, local dates, and local times are returned as strings since they have no timezone information and can't be losslessly represented as Date:

const data = toml.parse(`
odt = 1979-05-27T07:32:00Z       # Date object
ldt = 1979-05-27T07:32:00        # string: "1979-05-27T07:32:00"
ld  = 1979-05-27                  # string: "1979-05-27"
lt  = 07:32:00                    # string: "07:32:00"
`);

data.odt instanceof Date  // true
typeof data.ldt            // "string"
typeof data.ld             // "string"
typeof data.lt             // "string"

Temporal Support

Pass useTemporal: true to have date/time values returned as Temporal objects instead:

TOML type	Returned as
Offset date-time	Temporal.ZonedDateTime
Local date-time	Temporal.PlainDateTime
Local date	Temporal.PlainDate
Local time	Temporal.PlainTime

const data = toml.parse(`
odt = 1979-05-27T00:32:00-07:00
ldt = 1979-05-27T07:32:00
ld  = 1979-05-27
lt  = 07:32:00
`, { useTemporal: true });

data.odt.toString()  // "1979-05-27T00:32:00-07:00[-07:00]"
data.ldt.toString()  // "1979-05-27T07:32:00"
data.ld.toString()   // "1979-05-27"
data.lt.toString()   // "07:32:00"

Offset date-times become Temporal.ZonedDateTime values whose time zone is the original UTC offset (Z maps to the UTC time zone), so the offset written in the TOML document is preserved — unlike the default Date representation, which loses it. Fractional seconds beyond nanosecond precision are truncated, as permitted by the TOML spec.

useTemporal requires a runtime with the Temporal global. On runtimes that don't provide it yet, pass an implementation such as @js-temporal/polyfill via the temporal option:

const { Temporal } = require('@js-temporal/polyfill');
const data = toml.parse(someTomlString, { useTemporal: true, temporal: Temporal });

Once Temporal is broadly available, Temporal output is expected to become the default behavior in a future major version.

Special Float Values

inf and nan are returned as JavaScript Infinity and NaN:

const data = toml.parse(`
pos_inf = inf
neg_inf = -inf
not_a_number = nan
`);

data.pos_inf === Infinity   // true
data.neg_inf === -Infinity  // true
Number.isNaN(data.not_a_number) // true

Requiring .toml Files

You can use the toml-require package to require() your .toml files with Node.js.

Building & Testing

toml-node uses the Peggy parser generator (successor to PEG.js).

npm install
npm run build
npm test
npm run test:spec           # run toml-test compliance suite
npm run test:spec:failures  # show failure details

Changes to src/toml.pegjs require a rebuild with npm run build.

License

toml-node is licensed under the MIT license agreement. See the LICENSE file for more information.

Similar packages

Other packages similar to toml

toml-js

The 'toml-js' package is another library for parsing and stringifying TOML data. It offers similar functionality to the 'toml' package but may have different performance characteristics and API design.

tomlify-j0.4

The 'tomlify-j0.4' package focuses on converting JavaScript objects to TOML strings. It is useful if you primarily need to generate TOML data from JavaScript objects.

toml-node

The 'toml-node' package provides TOML parsing and stringifying capabilities. It is another alternative to the 'toml' package with its own implementation and features.