Below is the code for to find the first letter repeated in the string.
function findFirstRepeatLetter(str){
var letter = null
var obj = {}
for(var i=0;i<str.length;i++){
if(obj.hasOwnProperty(str[i])){
letter = str[i]
return letter
}else{
obj[str[i]]=1
}
}
return letter
}Thank you!
