Date.prototype.getMilliseconds()

An integer, between 0 and 999, representing the milliseconds for the given date according to local time. Returns NaN if the date is invalid.

The milliseconds variable has value 0, based on the value of the Date object xmas95, which doesn't specify the milliseconds component, so it defaults to 0.

const xmas95 = new Date("1995-12-25T23:15:30");
const milliseconds = xmas95.getMilliseconds();

console.log(milliseconds); // 0

• Date.prototype.getUTCMilliseconds()
• Date.prototype.setMilliseconds()