Lodash _.toNumber() Method

Beginner
5 min read
Updated: Nov 2026
5 examples
Lang
Decorative image with the word TONUMBER

Definition

Converts value to a number — the raw coercion under _.toFinite, _.toInteger, and friends. Can return NaN or ±Infinity. Part of Lodash 4.x Lang (since 4.0.0).

Pass the value you want to inspect or convert. Read the return type carefully before you use the result.

Syntax

Call _.toNumber. Start with this line.

Lodash
_.toNumber(value)
CallWhat it does
_.toNumber(value)Primary signature.

Prefer import toNumber from "lodash/toNumber" when you want a smaller bundle.

Library declarations
Lodash
_.toNumber(value)

Parameters

ParameterDescription
valueRequired. Any value to convert

Return Value

Return ValueDescription
*number (may be NaN / ±Infinity)

Lodash Examples

Example 1 — Docs: Number and Numeric String

Decimals stay decimals; numeric strings parse cleanly.

Lodash
_.toNumber(3.2);
// → 3.2

_.toNumber("3.2");
// → 3.2
Try It Yourself

How It Works

  1. Number. Already a number → returned as-is.
  2. String. Trimmed and parsed to 3.2.
  3. No truncate. Unlike toInteger, the fraction stays.
  4. Docs. Matches the common Lodash examples.

Example 2 — Docs: MIN_VALUE and Infinity

Tiny and infinite values are preserved — no sanitizing.

Lodash
_.toNumber(Number.MIN_VALUE);
// → 5e-324

_.toNumber(Infinity);
// → Infinity
Try It Yourself

How It Works

  1. MIN_VALUE. Already a finite number → kept.
  2. Infinity. Already a number → kept (not clamped).
  3. Contrast. toFinite(Infinity) would be MAX_VALUE.
  4. Role. This is the primitive; sanitizers wrap it.

Example 3 — null, undefined, Booleans, Symbol

Common myth: “nullish always becomes 0.” Only null does.

Lodash
_.toNumber(null);
// → 0

_.toNumber(undefined);
// → NaN

_.toNumber("");
// → 0

_.toNumber(true);
// → 1

_.toNumber(Symbol());
// → NaN
Try It Yourself

How It Works

  1. null. Same as +null → 0.
  2. undefined. Same as +undefined → NaN.
  3. Empty string. Parses as 0.
  4. Symbol. Short-circuits to NaN (no throw).

Example 4 — Prefixes, Trim, and valueOf

Literal prefixes and object hooks are the extras students ask about.

Lodash
_.toNumber("  7  ");
// → 7

_.toNumber("0x1f");
// → 31

_.toNumber("0b11");
// → 3

_.toNumber("0o17");
// → 15

_.toNumber("-0x10");
// → NaN

_.toNumber({ valueOf: function () { return 7; } });
// → 7
Try It Yourself

How It Works

  1. Trim. Leading/trailing spaces are removed first.
  2. Prefixes. Hex, binary, and octal literals parse like JS.
  3. Signed hex. "-0x10" is rejected → NaN.
  4. valueOf. Objects with a numeric valueOf coerce cleanly.

Example 5 — toNumber vs toFinite

Pick the sanitizer when you need a guaranteed finite number.

Lodash
_.toNumber(Infinity);
// → Infinity

_.toFinite(Infinity);
// → 1.7976931348623157e+308

_.toNumber(NaN);
// → NaN

_.toFinite(NaN);
// → 0

_.toNumber("abc");
// → NaN

_.toFinite("abc");
// → 0
Try It Yourself

How It Works

  1. Raw. toNumber reports what coercion produced.
  2. Sanitize. toFinite never returns NaN or Infinity.
  3. Bad strings. Both parse to NaN first; only toFinite maps to 0.
  4. Choose. Diagnostics → toNumber; math defaults → toFinite.
Compatibility

Browser & Runtime Support

_.toNumber is a Lodash 4.x Lang helper (since 4.0.0). It runs anywhere Lodash runs — modern browsers (CDN or bundle) and Node.js / Bun / Deno with npm install lodash. Closest natives are Number(value) / unary +; Lodash adds consistent string trimming, literal-prefix parsing, and the valueOf object path.

✓ Stable · Lodash 4.x

_.toNumber()

Available in [email protected] full builds and the lodash/toNumber modular import. Works in evergreen browsers and current Node LTS when Lodash is installed.

100% With Lodash 4.x
Google Chrome Supported · Desktop & Mobile
Full support
Mozilla Firefox Supported · Desktop & Mobile
Full support
Apple Safari Supported · macOS & iOS
Full support
Microsoft Edge Supported · Chromium
Full support
Internet Explorer No native support · Use a polyfill
Polyfill
Opera Supported · Modern versions
Full support
Samsung Internet Supported · Android
Full support
Bun Supported · JavaScript runtime
Supported
Deno Supported · JavaScript runtime
Supported
Node.js Supported · Server runtime
Supported
Android WebView Supported · Modern WebView
Full support
_.toNumber Lodash 4.x+

Bottom line: Safe for production once Lodash is loaded. Prefer import toNumber from "lodash/toNumber" for smaller builds. Reach for toFinite when you need a soft, always-finite result.

Frequently Asked Questions

_.toNumber(value) converts value to a JavaScript number. Unlike toFinite, it can return NaN or ±Infinity.
No. undefined → NaN. null → 0. If you want a soft 0 fallback, use _.toFinite.
Very similar for most inputs. Lodash trims strings and carefully parses 0x / 0b / 0o prefixes; objects go through valueOf first.
toNumber keeps NaN and Infinity. toFinite maps those to 0 and ±Number.MAX_VALUE.
Symbol becomes NaN. BigInt throws — convert explicitly first if you must.
Use import toNumber from "lodash/toNumber" or require("lodash/toNumber") for tree-shaking. Full build: import _ from "lodash" then _.toNumber.

Next: _.toPlainObject()

Flatten inherited enumerable properties onto a plain object.

_.toPlainObject() tutorial →

About the author

Mari Selvan M P
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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