[leetcode]389. Find the Difference -- JavaScript 代码

/**
* @param {string} s
* @param {string} t
* @return {character}
*/
var findTheDifference = function(s, t) {
var tlen = t.length;
var slen = s.length;
var ret = 0;
for(var i=0;i<slen;i++){
ret ^= s.charCodeAt(i);
}
for(i=0;i<tlen;i++){
ret ^= t.charCodeAt(i);
}
return String.fromCharCode(ret);
};