Can any one please explain this code for me

Question

function join(arr) {
var str = arr[0];//oven
var min = arr[0].length;//4
for(let i=1;i<arr.length;i++){
let strIndex = str.length-1;//3
let nextIndex = 0;
//n!=
while(str[strIndex] != arr[i][nextIndex]){
nextIndex++;
if(nextIndex == arr[i].length)
break;
}
if(nextIndex == arr[i].length){
str += arr[i];
min = 0;
continue;
}
var matchCount = 0;
var matchIndex = nextIndex;
while(str[strIndex] == arr[i][matchIndex]){
strIndex--;
matchIndex--;
matchCount++;
}
if(matchCount < min)
min = matchCount
str += String(arr[i]).substr(nextIndex + 1);
}
return [str,min];
}

console.log(join(["oven","envier","erase","serious"]))

Answer 1

Where did he come from?