what is the meaning of

respected sir..
what is the meaning of these two lines

var brVerid=brVer.indexOf('MSIE');
brNum=brVer.substr(brVerid,8);

Hi Neeraj,

indexOf() - Returns the position of the first found occurrence of a specified value in a string

substr() - Extracts the characters from a string, beginning at a specified start position, and through the specified number of character

It means in the above case,
if brVer = ahbvhfadfbkajf...MSIE....sgfhgakhdghk,

var brVerid=brVer.indexOf('MSIE'); // this will get start position
brNum=brVer.substr(brVerid,8); // here we are using that result to get substring.