^ (Caret) and ~ (Tilde) in package.json

You must have seen at least once package.json file throughout your developer journey.
package.json is a file that contains information about a project, among which are project dependencies and their corresponding versions.
But then, you must have noticed that some versions have ^ (caret) or ~ (tilde) in front of them. What are they for and what do they mean?

REMINDER: x.x.x format

Example:

"pg": "8.7.3"

The x.x.x format you see in version numbers follows this structure:

MAJOR.MINOR.PATCH

So, in the example above:

• 8 - MAJOR
• 7 - MINOR
• 3 - PATCH

~ (Tilde) - Patch Updates

• Allows only patch updates within the same minor version.

"mongoose": "~6.2.2"

Allows updates up to 6.2.x, but not 6.3.0.
Here, it will install new versions like 6.2.3, 6.2.7, 6.2.9, but it will not install 6.3.0.

Why use ~?

For backend libraries, especially security-related ones, developers often want to allow only patch updates to avoid breaking API changes.

^ (Caret) - Minor and Patch Updates

• Allows updates only within the same major version, meaning it allows only minor and patch updates.

"react": "^18.2.0"

Allows 18.2.0 up to 18.x.x, but not 19.0.0.
Here it will install new versions like 18.2.3, 18.3.4, 18.5.2, 18.8.6, but it will not install 19.0.0.

Why use ^?

Frontend libraries frequently release minor updates, so ^ helps get the latest bug fixes and performance improvements without breaking the major version.

Summary

Symbol	Example	Allowed Updates
^	^4.17.21	4.17.21 → 4.x.x (not 5.0.0)
~	~4.17.1	4.17.1 → 4.17.x (not 4.18.0)