gistfile1.js

var womanHeightList = [155,157,160,163,165,168,170,171,173,175,178,180,183];

var increaseButtonStream = $('.btn-size.add').asEventStream('click');
var decreaseButtonStream = $('.btn-size.delete').asEventStream('click');
var counterStream = increaseButtonStream.map(1).merge(decreaseButtonStream.map(-1)).scan(0, function (acc, x){
    var sum = acc + x;
    if (sum<0) sum = womanHeightList.length-1;
    if (sum>womanHeightList.length-1) sum = 0;
    return sum;
});
var counterTextStream =  counterStream.map(function(value){
    return womanHeightList[value];
});
var imageHeightStream =  counterStream.map(function(value){
    var humanHeight = womanHeightList[value] * pxPerSm;
    return humanHeight;
});

counterTextStream.assign($('.current-height'), 'text');
imageHeightStream.assign($('.human'), 'height');