let arr = ["38:21","33:12","11:22"],obj = {};

for(let i = 0 ; i < arr.length;i++){
    let temp = arr[i].split(':');
        obj[temp[0]]=temp[1];        
}

console.log(obj);

var source = ["38:21", "33:12", "11:22"];
var target = {};
for (var i = 0; i < source.length; i++) {
    var tmpSplitArray = source[i].split(":");
    target[tmpSplitArray[0]] = parseInt(tmpSplitArray[1]);
}
console.log(target);

["38:21","33:12","11:22"].map(o=>{
   let kv = o.split(":");
   return {[kv[0]]:kv[1]}
})