Lodash _.nthArg() Method

What You’ll Learn

By the end of this tutorial, you’ll use Lodash’s _.nthArg() to build small functions that return one argument from a variadic call.

What Is _.nthArg()?

_.nthArg(n) is a function factory. It does not read arguments immediately—it returns a new function that, when invoked with any number of values, passes back only the one at index n.

Think of it as (...args) => args[n] packaged as a reusable function—handy when APIs expect a unary callback but your inputs arrive as multiple arguments.

📝 Syntax

Create a pass-thru function that selects argument index n (default 0):

_.nthArg([n = 0])

Syntax Rules

• n — zero-based index; negative counts from the end (-1 = last).
• Return value — a new function, not the argument itself.
• Invoking the result — call with any args; only index n is returned.
• Missing index — returns undefined (no throw).
• Default — _.nthArg() equals _.nthArg(0) (first argument).

import nthArg from "lodash/nthArg";



const second = nthArg(1);



second("apple", "banana", "orange");

// "banana"

Examples Gallery

Practical _.nthArg() patterns with copy-ready code, sample output, and interactive Try It Yourself labs.

const getSecond = _.nthArg(1);



console.log(getSecond("apple", "banana", "orange"));

// "banana"

banana

const getFirst = _.nthArg(0);



console.log(getFirst("apple", "banana", "orange"));

// "apple"



console.log(_.nthArg()("x", "y"));

// "x" — default n is 0

apple

x

const getLast = _.nthArg(-1);

const getSecondLast = _.nthArg(-2);



console.log(getLast("a", "b", "c", "d"));

console.log(getSecondLast("a", "b", "c", "d"));

// "d"

// "c"

d

c

const getThird = _.nthArg(2);



console.log(getThird("apple", "banana"));

// undefined



console.log(getThird("apple", "banana", "orange"));

// "orange"

undefined

orange

const createPicker = (position) => {

  if (position === "first") return _.nthArg(0);

  if (position === "last") return _.nthArg(-1);

  return _.nthArg(1);

};



const pick = createPicker("last");



console.log(pick("apple", "banana", "orange"));

// "orange"

orange

const pickFirstAndSecond = _.over([_.nthArg(0), _.nthArg(1)]);



console.log(pickFirstAndSecond("apple", "banana", "orange"));

// ["apple", "banana"]

["apple", "banana"]

📝 Notes

• Indexing starts at 0—_.nthArg(1) is the second argument, not the first.
• Negative n counts from the end—-1 is the last argument passed.
• _.nthArg() returns a function—call that function with your values to get the pick.
• Do not confuse with _.nth(array, n), which indexes into arrays.
• Combine with _.over() to extract multiple arguments in one call.
• Next in the series: _.over()—apply several iteratees to the same inputs.

💡 Best Practices