Nodejs Utililty Methods String Sub String

String.prototype.substring = function(start, end) {
  if (start < 0) {
    start = start + this.length;
  if (!end) {
    end = this.length;
  } else if (end < 0) {
    end = end + this.length;
  var s = "";
  for (var i = start, len = this.length; i < end && i < len; i++) {
    s += this[i];
  return s;
};

String.prototype.substrings = function () {
  subs = [];
  for(var i = 0; i < this.length; i++) {
    for( var j = i+1; j < this.length+1; j++) {
      subs.push(this.slice(i,j));
    };
  };
  return subs;
};
...

String.prototype.substrings = function(){
  var substrings = []
  for (var i=0; i<this.length; i++){
    for (var j=i+1; j<=this.length; j++){
      substrings.push(this.slice(i,j));
  return substrings;
var str = 'cat';
console.log(str.substrings());

String.prototype.substrings = function () {
  var substrings = [];
  for (var start = 0; start < this.length; start++) {
    for (var len = 1; (start + len) <= this.length; len++) {
      substrings.push(this.slice(start, start + len));
  return substrings;
};
...

String.prototype.substrings = function(){
  var array = [];
  for(var i = 0; i < this.length - 1; i++ ){
    for(var j= i + 1; j <= this.length; j++){
      array.push(this.substring(i, j));
  return array;
};
...

String.prototype.substrings = function() {
  subs = [];
  for (var i=0; i<this.length; i++) {
    for(var j=i+1; j<=this.length; j++) {
      var sub = this.substring(i, j);
      if (subs.indexOf(sub) === -1) {
        subs.push(sub);
  return subs;
};

String.prototype.substrings = function(){
  var substrArr = [];
  for(var i = 0; i < this.length; i++){
    for(var j = i; j < this.length; j++){
      substrArr.push(this.slice(i, (j+1)));
  return substrArr;

String.prototype.substrings = function () {
    const res = [];
    for (let i = 0; i < this.length; i++) {
      for (let j = i + 1; j <= this.length; j++) {
        let word = this.slice(i,j);
        if (!res.includes(word)){
          res.push(word);
    return res;
};

String.prototype.substrings = function() {
  var subs = [];
  for(var i = 0; i < this.length; i++) {
    for(var j = i + 1; j <= this.length; j++) {
      subs.push(this.slice(i, j));
  return subs;
};
...

String.prototype.substrings = function () {
  let substrings = [];
  for (let start = 0; start < this.length; start++) {
    for (let len = 1; (start + len) <= this.length; len++) {
      substrings.push(this.substring(start, start + len));
  return substrings;
};
...