amd.js
function strSplice(str, index, count, add) {
  return str.slice(0, index) + add + str.slice(index + count);
}
function strSplice(str, index, count, add) {
  return str.slice(0, index) + add + str.slice(index + count);
}
function strSplice ( str , index , count , add ) { return str . slice ( 0 , index ) + add + str . slice ( index + count ) ; }
like array.splice
like array . splice