Patched a vulnerability in useragent library

The "useragent" library used in the SDK has a vulnerability when the user agent string is too long (as the result of hacking attempt). This version patches it when the SDK uses the library.

Minor type declaration fix

Added a fix for environment type in the type declaration file index.d.ts

v4.5.3 - Backfill support for node v12+

The SDK now uses tsc to transpile the javascript and pollyfill the SDK to work with older versions of node.

v4.5.1 Allow undefined values to be set in user.custom and user.privateAttributes

Allows undefined values to be set in user.custom and user.privateAttributes. You cannot create gate conditions to target undefined values, and they are ignored at evaluation time. This is a quality of life typing change

Changes related to experiment exposures

1. We have been calculating secondary exposures (exposures on dependent feature gates) in Statsig backend. With this release we are moving the logic to SDK evaluator so that it's more accurate and efficient.
2. Changed ruleID to "disabled" when evaluating a disabled feature

Fix retry logic

Fixed a bug where we keep retrying forever on failed initialize network requests

Align evaluation behavior for string based operators

We are aligning the behavior for all string based operators in this release so that we try to convert accidentally provided incorrect types to strings and evaluate instead of returning false by default.

New operators and improvements

• Added support for "string contains none" operator.
• Improved the logic to update evaluation rule sets so that it's less likely the rule sets stay stale for any extended period of time.
• Moved exposure logging for "fetch from server" fallback case from SDK to statsig server

v4.4.0 - adding support for private user attributes

We are adding support for private user attributes with this release. privateAttributes can be set on StatsigUser and any info set in it will only be used for evaluation/targeting purposes, and removed from any logs sent to Statsig server. See more info at https://docs.statsig.com/server/nodejsServerSDK#private-attributes

Improvements to certain condition evaluations

• swapped out the user agent parser to a different one so that all of Statsig's server SDKs are using the same core regex to parse UA strings and will get the same results.
• added support for string case sensitive comparisons