a = [1, 2, -17, 99]
min_idx = a.index(min(a))

##</code><code>##

a = [1, 2, -17, 99]
min_idx = a.index(a.min)

##</code><code>##

var a = [1, 2, -17, 99];
var min_idx = a.indexOf(Math.min.apply(Math, a));