I'm trying to convert 15:00 (15minutes) to seconds though I get 54,000 when I use this below. 

I'm trying to convert 15minutes to seconds.

```
S = '15:00';
D = "1/1/1 "
s = ( new Date(D+S) - new Date(D) )/1000
alert(s);

```

Though when I do the math, it's 60 x 15 = 900. How do I get 900, since the time is a random string.