Reusing variables between different versions of Moment.js and Moment Timezone resulted in spectacular bugs

Mixing Moment.js and Moment Timezone versions broke date handling due to how the _d property is treated.

[Moment Timezone] How to Use moment.tz

The two Moment Timezone interfaces — moment.tz(..., String) and moment().tz(String) — with code samples.

moment-timezone old version caused date processing bugs during daylight saving time switch

An old moment-timezone bugged out at the DST switch — upgrading fixed it, and here's why tz updates matter.