Javascript is fun

```javascript
a = new Date('2019-03-31T00:00:00.000Z');
a.setDate(a.getDate() + 1);
console.log(a);
```

| Firefox macos | Safari macos | chrome macos |
|-------------|---------------|------------------|
| 2019-**03-31**T23:00:00.000Z | Mon Apr 01 2019 00:00:00 GMT+0100 (BST)|Mon Apr 01 2019 00:00:00 GMT+0100 (British Summer Time)

however, 

```javascript
a = new Date('2019-03-31T00:00:00.000Z');
b = new Date(a.getTime()+1000*60*60*24);
console.log(b);
```

| Firefox macos | Safari macos | chrome macos |
|-------------|---------------|------------------|
| 2019-**04-01**T00:00:00.000Z| Mon Apr 01 2019 01:00:00 GMT+0100 (BST) |Mon Apr 01 2019 01:00:00 GMT+0100 (British Summer Time)|