const date1 = new Date('2018-01-24T12:38:29.069Z');
console.log(date1.getUTCMilliseconds());
// expected output: 69
date1.setUTCMilliseconds(420);
console.log(date1.getUTCMilliseconds());
// expected output: 420
const date1 = new Date('2018-01-24T12:38:29.069Z');console.log(date1.getUTCMilliseconds());// expected output: 69date1.setUTCMilliseconds(420);console.log(date1.getUTCMilliseconds());// expected output: 420