dump() & dd()

dump()

Prints a formatted value to the terminal.

Syntax

dump(value: unknown, options?: DumpOptions): unknown

Parameters

Parameter	Type	Description
value	unknown	The value to dump
options	DumpOptions	Configuration options (optional)

Return value

Returns the original value unchanged - enables chaining.

Options

Option	Type	Default	Description
view	'flat' | 'tree' | 'table'	'flat'	Visualisation style
depth	number	30	Maximum nesting depth
colors	boolean	auto	true = force colors, false = no colors, auto = TTY-based
showHidden	boolean	false	Show non-enumerable properties
maxArrayLength	number	1000	Maximum array items to display
maxStringLength	number	5000	Maximum string length
indent	number	2	Spaces per indentation level
stream	WriteStream	stderr	Output stream

Examples

Basic usage (flat view)

dump({ name: 'John', age: 30 });

Output:

{
  name: "John",
  age: 30
}

Tree view

const data = {
  name: 'John',
  address: {
    city: 'Lisbon',
    street: 'Augusta'
  }
};

dump(data, { view: 'tree' });

Output:

Object
├── name: "John"
└── address: Object
    ├── city: "Lisbon"
    └── street: "Augusta"

Table view (array of objects)

const users = [
  { name: 'Alice', age: 30, city: 'Lisbon' },
  { name: 'Bob', age: 25, city: 'Porto' }
];

dump(users, { view: 'table' });

Output:

name   | age | city
───────┼─────┼───────
Alice  | 30  | Lisbon
Bob    | 25  | Porto

With limited depth

const deep = { a: { b: { c: { d: 'deep' } } } };
dump(deep, { depth: 2 });

Output:

{
  a: {
    b: [Object]
  }
}

Without colors

dump({ error: 'Failed' }, { colors: false });

Output (no ANSI codes):

{
  error: "Failed"
}

Chaining

const result = dump(user).process();
// The value of user is printed, then process() is called

Custom stream

import { createWriteStream } from 'fs';
const stream = createWriteStream('./debug.log');
dump(data, { stream });
// Output is written to debug.log file

---

dd()

Dump and die - prints the value and terminates the process.

Syntax

dd(value: unknown, options?: DumpOptions): never

Parameters

Parameter	Type	Description
value	unknown	The value to dump
options	DumpOptions	Configuration options (optional)

Return value

Never returns - calls process.exit(1).

Examples

Basic usage

function handler(req) {
  dd(req);
  // This code never runs
}

Output:

{
  method: "GET",
  url: "/api/users"
}

(Process terminates after output)

Conditional debugging

if (error) {
  dd({ error, context: 'api-failure' });
}

---

Differences between dump() and dd()

Function	Output	Continues execution?
dump()	Prints value	✅ Yes
dd()	Prints value	❌ No (process.exit)

Tips

• Use dump() to inspect values during normal flow
• Use dd() to stop execution at a specific point
• Use view: 'tree' to understand nested structures
• Use view: 'table' for arrays of homogeneous objects
• Chaining with dump() enables non-intrusive debugging:

const result = dump(process(data)).transform();
// The value of process(data) is shown, but transform() is still called