Quickstart

The simplest way to use Datadance is with the transform function.

Basic example

When you call transform, you provide your data (input), the operations to perform (transforms), and how to merge the result (settings).

Input

{
  "name": "Alice",
  "score": 85
}

Output

{
  "name": "ALICE",
  "score": 100,
  "grade": "B"
}

Transforms (JSON)

[
  { "name": "upper(input.name)" },
  { "score": "input.score + 15" },
  { "grade": "input.score >= 90 ? 'A' : 'B'" }
]

Transforms (DDS)

name: upper(input.name)
score: input.score + 15
grade: input.score >= 90 ? 'A' : 'B'

Transform structure

Each transform is an object with exactly one key. The key is the output field name, and the value is either a MozJexl expression string or an array of nested transforms.

Merge methods

The merge_method setting controls how the output is combined with the input:

Method	Behaviour
overwrite	Transformed fields replace matching input keys. Unchanged input fields are preserved.
preserve	Original input is returned as-is. Transformed fields are nested under a transforms key.
transforms_only	Only transformed fields are returned. All input data is discarded.

Using DDS syntax

Instead of JSON, you can write transforms in Datadance Syntax (DDS), a YAML-like format:

DDS

name: upper(input.name)
score: input.score + 15

JavaScript

const result = await transform({
  input: { name: "Alice", score: 85 },
  transforms: "name: upper(input.name)\nscore: input.score + 15",
  settings: { merge_method: "overwrite", transforms_syntax: "dds" },
});

Interactive Playground

Try it live in the Playground — edit input, write transforms, and see results instantly.