Lodash Lang Methods

Beginner

7 min read

Updated: Nov 2026

56 method guides

Method index

Index

About This Index

This page is the Lodash Lang index for the tutorial track. Each row links to a full guide with syntax, examples, and FAQs.

Learn functions and collections on /lodash/function and /lodash/collection. Use this page when you need type checks or conversions such as _.isEqual(), _.cloneDeep(), or _.isNil().

Beginner path.

Start with _.isEqual(), then _.cloneDeep(), _.isNil(), and _.isArray()—then browse convert helpers as needed.

Syntax

How to Call a Lang Method

Pass a value (and any extra arguments) to the Lodash helper:

Lodash

import _ from "lodash";

_.isArray([1, 2, 3]);           // true
_.isNil(null);                  // true
_.isEqual({ a: 1 }, { a: 1 });  // true

const original = { nested: { n: 1 } };
const copy = _.cloneDeep(original);
copy.nested.n = 2;
// original.nested.n is still 1

_.toNumber("3.14");  // 3.14
_.toString([1, 2]);  // "1,2"
_.castArray(1);      // [1]

Browse

Lodash Lang Methods Table

All lang method guides in this Lodash tutorial series (56 tutorials).

Clone & Cast

5 methods

Shallow and deep clones, plus castArray for array wrapping.

Method	Description	Tutorial
`_.castArray()`	Wrap a value in an array unless it is already an array.	Try it
`_.clone()`	Create a shallow clone of a value.	Try it
`_.cloneDeep()`	Create a deep clone of a value recursively.	Try it
`_.cloneDeepWith()`	Deep clone with a customizer for special cases.	Try it
`_.cloneWith()`	Shallow clone with a customizer override.	Try it

Compare & Match

10 methods

Equality, ordering, and partial object matching.

Method	Description	Tutorial
`_.eq()`	Compare two values with SameValueZero semantics.	Try it
`_.gt()`	Check if the first value is greater than the second.	Try it
`_.gte()`	Check if the first value is greater than or equal to the second.	Try it
`_.lt()`	Check if the first value is less than the second.	Try it
`_.lte()`	Check if the first value is less than or equal to the second.	Try it
`_.isEqual()`	Perform a deep equality comparison.	Try it
`_.isEqualWith()`	Deep equality comparison with a customizer.	Try it
`_.isMatch()`	Check if an object partially matches source properties.	Try it
`_.isMatchWith()`	Partial match check with a customizer.	Try it
`_.conformsTo()`	Check if an object conforms to source predicates.	Try it

Nullish & Empty

4 methods

Null, undefined, nil, and empty checks.

Method	Description	Tutorial
`_.isNil()`	Check if a value is null or undefined.	Try it
`_.isNull()`	Check if a value is null.	Try it
`_.isUndefined()`	Check if a value is undefined.	Try it
`_.isEmpty()`	Check if a collection, map, set, or object is empty.	Try it

Core Type Checks

9 methods

Common primitives and object shapes.

Method	Description	Tutorial
`_.isArray()`	Check if a value is an array.	Try it
`_.isBoolean()`	Check if a value is classified as a boolean.	Try it
`_.isFunction()`	Check if a value is classified as a function.	Try it
`_.isNumber()`	Check if a value is classified as a number.	Try it
`_.isString()`	Check if a value is a string.	Try it
`_.isObject()`	Check if a value is the language type of Object.	Try it
`_.isObjectLike()`	Check if a value is object-like (not null, typeof object).	Try it
`_.isPlainObject()`	Check if a value is a plain object.	Try it
`_.isSymbol()`	Check if a value is a symbol.	Try it

Number Quality

5 methods

Finite, integer, safe integer, NaN, and length checks.

Method	Description	Tutorial
`_.isFinite()`	Check if a value is a finite primitive number.	Try it
`_.isInteger()`	Check if a value is an integer.	Try it
`_.isSafeInteger()`	Check if a value is a safe integer.	Try it
`_.isNaN()`	Check if a value is NaN (number only).	Try it
`_.isLength()`	Check if a value is a valid array-like length.	Try it

Built-in Type Checks

15 methods

Arrays, maps, sets, dates, errors, buffers, and related types.

Method	Description	Tutorial
`_.isArguments()`	Check if a value is likely an arguments object.	Try it
`_.isArrayBuffer()`	Check if a value is an ArrayBuffer.	Try it
`_.isArrayLike()`	Check if a value is array-like (has length, not a function).	Try it
`_.isArrayLikeObject()`	Check if a value is object-like and array-like.	Try it
`_.isBuffer()`	Check if a value is a Node.js Buffer.	Try it
`_.isDate()`	Check if a value is a Date object.	Try it
`_.isElement()`	Check if a value is likely a DOM element.	Try it
`_.isError()`	Check if a value is an Error object.	Try it
`_.isMap()`	Check if a value is a Map object.	Try it
`_.isSet()`	Check if a value is a Set object.	Try it
`_.isWeakMap()`	Check if a value is a WeakMap object.	Try it
`_.isWeakSet()`	Check if a value is a WeakSet object.	Try it
`_.isRegExp()`	Check if a value is a RegExp object.	Try it
`_.isTypedArray()`	Check if a value is a typed array.	Try it
`_.isNative()`	Check if a value appears to be a native function.	Try it

Convert

8 methods

Normalize values to arrays, numbers, strings, and plain objects.

Method	Description	Tutorial
`_.toArray()`	Convert a value to an array.	Try it
`_.toFinite()`	Convert a value to a finite number.	Try it
`_.toInteger()`	Convert a value to an integer.	Try it
`_.toLength()`	Convert a value to a valid array-like length.	Try it
`_.toNumber()`	Convert a value to a number.	Try it
`_.toPlainObject()`	Convert a value to a plain object flattening inherited props.	Try it
`_.toSafeInteger()`	Convert a value to a safe integer.	Try it
`_.toString()`	Convert a value to a string.	Try it

Frequently Asked Questions

What are Lodash lang methods?

They are language-level helpers for inspecting values, comparing deeply (_.isEqual), cloning (_.clone / _.cloneDeep), checking types (_.isArray, _.isNil), and converting unknowns (_.toNumber, _.toString).

What is the difference between isNil, isNull, and isUndefined?

_.isNil matches null or undefined. _.isNull only matches null. _.isUndefined only matches undefined.

When should I use _.cloneDeep?

Use it when nested objects or arrays must not share references with the original. Prefer _.clone for shallow copies when nested sharing is fine—deep clones can be expensive on large graphs.

How should I import Lodash lang methods?

Prefer per-method imports: import isEqual from 'lodash/isEqual' or import { isEqual } from 'lodash-es'. You can also use const _ = require('lodash') and call _.isEqual().

Where should I start?

Start with _.isEqual(), then _.cloneDeep(), _.isNil(), and _.isArray() from the table below.

Start with _.isEqual()

Open the deep equality guide—syntax, examples, and FAQs.

_.isEqual() tutorial →

About the author

Mari Selvan M P 🔗

Developer, cloud engineer, and technical writer

Experience 12 years building web and cloud systems
Focus Full Stack Development, AWS, and Developer Education

I write practical tutorials so students and working developers can learn by doing—from databases and APIs to deployment on AWS.

AWS Certified Developer – Associate (Credly)

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Lodash Function Methods Lodash _.castArray() Method