Getting the maximum value from an array in a JSON response in Karate - karate

Question

I have the following Json as a response from a API call
{
"location": {
"name": "London",
"region": "City of London, Greater London",
"country": "United Kingdom",
"lat": 51.52,
"lon": -0.11,
"tz_id": "Europe/London",
"localtime_epoch": 1583594426,
"localtime": "2020-03-07 15:20"
},
"forecast": {
"forecastday": [
{
"date": "2020-03-03",
"day": {
"maxtemp_c": 9,
"mintemp_c": 4
}
},
{
"date": "2020-03-04",
"day": {
"maxtemp_c": 8,
"mintemp_c": 4.1
}
},
{
"date": "2020-03-05",
"day": {
"maxtemp_c": 7,
"mintemp_c": 5.6
}
}
]
}
}
I want to find out which date had the highest temperature amongst the 3 days.
The way I am currently doing feels inefficient as I am checking for the temperature element within my js function and it is as follows
* def hottest =
"""
function(array) {
var greatest;
var indexOfGreatest;
for (var i = 0; i < array.length; i++) {
if (!greatest || array[i].day.maxtemp_c > greatest) {
greatest = array[i].day.maxtemp_c;
indexOfGreatest = i;
}
}
return indexOfGreatest;
}
"""
* def index = call hottest response.forecast.forecastday
* def hottestdate = response.forecast.forecastday[index].date
* print hottestdate
With this I am getting the correct result but can someone kindly suggest a better way of doing this?

Answer 1

Best practice in Karate is to NOT use JS for loops at all. It results in cleaner, more readable code:
* def fun = function(x){ return { max: x.day.maxtemp_c, date: x.date } }
* def list = karate.map(response.forecast.forecastday, fun)
* def max = 0
* def index = 0
* def finder =
"""
function(x, i) {
var max = karate.get('max');
if (x.max > max) {
karate.set('max', x.max);
karate.set('index', i);
}
}
"""
* karate.forEach(list, finder)
* print 'found at index', index
* print 'item:', list[index]
Note how easy it is to re-shape a given JSON, the result of list here would be:
[
{
"max": 9,
"date": "2020-03-03"
},
{
"max": 8,
"date": "2020-03-04"
},
{
"max": 7,
"date": "2020-03-05"
}
]