nthArg()

nthArg(n): (...args) => unknown

Creates a function that gets the argument at index n.

DEPRECATED

Use an inline arrow function (...args) => args[n] instead.

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Parameters

n: number

The index of the argument to return.

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Returns

A function that returns the nth argument.

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Since

2.0.0

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Also known as

nthArg (Lodash, es-toolkit, Ramda) · ❌ (Remeda, Radashi, Effect, Modern Dash, Antfu)

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Example

// ❌ Deprecated approach
const getSecond = nthArg(1);
getSecond('a', 'b', 'c');  // => 'b'

// ✅ Recommended approach
const getSecond = (...args: string[]) => args[1];
getSecond('a', 'b', 'c');  // => 'b'

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How it works?

Creates a function that gets the argument at index n. Deprecated: Use an arrow function.

Native Equivalent

// ❌ nthArg(1)
// ✅ (...args) => args[1]

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Use Cases

Extract specific argument 📌

Create function that returns nth argument.

#argument#extract#nth#function

const getSecond = (...args: unknown[]) => args[1];
getSecond('a', 'b', 'c');  // 'b'

Callback adapter

Adapt callback to use specific argument.

#callback#adapter#argument#select

// Get just the index from map callback
const getIndex = (_: unknown, i: number) => i;
['a', 'b', 'c'].map(getIndex);  // [0, 1, 2]