求大神解析其中的意思？

Question

for( var i =0;i<arr.length;i++ ){
    var index = arr[i].indexOf(':'); 
    sum += parseInt(  arr[i].substr(index+1,2)  );  

}

Answer 1

第一句，循环的条件；第二句，把“：”首次出现的位置赋值给index；第三句，同sum =sum+parseInt(  arr[i].substr(index+1,2)  )，其中arr[i].substr(index+1,2) 把字符串中“：”出现之后两个字符取出来，parseInt(  arr[i].substr(index+1,2)  )把取出来的两个字符转换成数字类型以用于计算。

Answer 2

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