Javascript String contains(str)

String.prototype.contains = function(str) {
  return this.indexOf(str) > -1;
};

String.prototype.contains = function (str) {
    return this.indexOf(str, 0) != -1;
}

String.prototype.contains = function(str) {
  return this.toLowerCase().indexOf(str.toLowerCase()) > -1;
};

String.prototype.contains = function(str) {
    if (typeof str !== 'string') return false;
    return this.indexOf(str) !== -1;
};

String.prototype.contains = function(str){
 var filters = str.toLowerCase().split(/[ ,_\-]+/);
 var tokens = this.toLowerCase().split(/[ ,\-]+/);
 for (var i = 0; i < filters.length; i++) {
  var match = false;
  for (var j = 0; j < tokens.length; j++) {
   if (tokens[j].startsWith(filters[i])) {
    match = true;//w w  w  .  jav a 2s. co  m
    break;
   }
  }
  if (match == false) {
   return false;
  }
 }
 return true;
}

String.prototype.contains = function(str){     
   if(this.indexOf(str) != -1){
    return true;//from  ww w.j a va2 s  . c  o m
   }  
   return false;
}


String.prototype.insert = function(flg, offset){
    var temp_1 = this.substring(0, offset + 1);
    var temp_2 = this.substring(offset + 1);
    return temp_1 + flg + temp_2;
}