Two variables in an alert

JavaScript
1 
<script type="text/javascript">

var myvar1 = 'Hello!';
var myvar2 = 'Hi!'
alert(myvar1);
alert(myvar2);

</script>

The code above pops two alerts.

The 1st alert says ‘Hello!.’
The 2nd alert says ‘Hi!.’

I like to make it like the following.

It pops an alert instead of two alerts saying ‘Hello! Hi!.’

2 

alert(myvar1 + ' ' + myvar2);
3

Thanks you. it works fine.