JSFiddle - React, Tailwind, and code Playground

JavaScript

var homeTeamOppw = {"last_gp": 0.2, "2nd_gp": 0.2, "3rd_gp": 0.8, "4th_gp": 0.4, "5th_gp": 0.8};
ans = {val:0};

function timesArrayitems(teamOpp, array){

var num = 1;

for(item in array){

    num = num * array[item];
}
    
    teamOpp.val = num;

}

 timesArrayitems(ans, homeTeamOppw);
 console.log(ans);