[Regular Expressions] Match the Start and End of a Line

We can use:

^: match the beginning
$: match the end

Let's say we have the string like the following:

var str = `//
--
//
--`;

What we want to do is get all the '12' which at the begining of each line:

If we do like that:

var regex = /^/g;

To solve this problem, we can use 'm' flag:

var regex = /^/gm;

And also we want to get the line which end by '16':

var regex = /^.+$/gm;