returning...

sample.js

if(this.model.site){
  var options_list = this.config.fields.site.options;
  var selectVal = _.find(options_list,['id',this.model.site]);
  if(selectVal && this.model.name){
        return (this.model.name.toLowerCase().indexOf(selectVal.label.toLowerCase()) === 0) ;
  }
  else{
    return false;
  }
}
else{
  return false;
}

// can be

if(this.model.site){
  var options_list = this.config.fields.site.options;
  var selectVal = _.find(options_list,['id',this.model.site]);
  if(selectVal && this.model.name){
    return (this.model.name.toLowerCase().indexOf(selectVal.label.toLowerCase()) === 0) ;
  }
}
return false;