Data Transform

convert.js

Convert between data formats.

Usage:

node convert.js <input> --to <format> [OPTIONS]

Formats:

• json - JSON
• csv - Comma-separated values
• tsv - Tab-separated values
• yaml - YAML
• xml - XML
• markdown - Markdown table
• html - HTML table

Options:

• --to <format> - Target format (required)
• --from <format> - Source format (auto-detected if not specified)
• --output <file> - Save to file
• --pretty - Pretty print output

query.js

Query and filter data using JSONPath or JQ-like syntax.

Usage:

node query.js <input> <query> [OPTIONS]

Query Syntax:

• $.field - Access field
• $.array[0] - Array index
• $.array[*] - All array elements
• $.array[?(@.age > 18)] - Filter
• $..name - Recursive descent

Options:

• --format <fmt> - Input format (default: auto)
• --output <fmt> - Output format: json, csv, lines (default: json)

parse.js

Parse data files with format detection.

Usage:

node parse.js <input> [OPTIONS]

Options:

• --format <fmt> - Force input format
• --validate - Validate and report errors
• --schema <file> - Validate against JSON schema

transform.js

Apply transformations to data.

Usage:

node transform.js <input> --map <expression>
node transform.js <input> --filter <expression>
node transform.js <input> --sort <field>

Options:

• --map <expr> - Transform each item (JS expression)
• --filter <expr> - Filter items (JS expression)
• --sort <field> - Sort by field
• --reverse - Reverse order
• --unique <field> - Remove duplicates
• --group <field> - Group by field
• --limit <n> - Limit results

diff.js

Compare two data files.

Usage:

node diff.js <file1> <file2> [OPTIONS]

Options:

• --format <fmt> - Output format: unified, json, side-by-side
• --ignore-order - Ignore array order
• --ignore-case - Case-insensitive comparison

Examples

Convert JSON Array to CSV

echo '[{"name":"John","age":30},{"name":"Jane","age":25}]' | node convert.js - --to csv

Output:

name,age
John,30
Jane,25

Query Nested Data

node query.js api-response.json "$.data.users[?(@.active==true)].email"

Transform Data

node transform.js users.json --filter "x.age >= 18" --sort age --map "{name: x.name, adult: true}"

CSV to Markdown Table

node convert.js report.csv --to markdown

Output:

| Name | Score |
|------|-------|
| Alice | 95 |
| Bob | 87 |

Compare JSON Files

node diff.js old-config.json new-config.json --format unified

Validate JSON Against Schema

node parse.js data.json --validate --schema schema.json

Supported Formats

Output Formats

query.js (JSON mode)

{
  "query": "$.users[*].name",
  "results": ["John", "Jane", "Bob"],
  "count": 3
}

diff.js (JSON mode)

{
  "added": [{"path": "$.newField", "value": "new"}],
  "removed": [{"path": "$.oldField", "value": "old"}],
  "changed": [{"path": "$.field", "old": 1, "new": 2}],
  "unchanged": 10
}