Step by Step solution about How to resolve the algorithm 99 bottles of beer step by step in the JavaScript programming language

The provided code is a collection of different ways to implement the lyrics of the song "99 Bottles of Beer on the Wall" in JavaScript. Here's a detailed breakdown of each approach:

1. Using a while loop and string concatenation:

   var beer = 99;
   while (beer > 0) {
    var verse = [
      beer + " bottles of beer on the wall,",
      beer + " bottles of beer!",
      "Take one down, pass it around",  
      (beer - 1) + " bottles of beer on the wall!"
    ].join("\n");
   
    console.log(verse);
   
    beer--;
   }

   This code uses a while loop to iterate from 99 down to 0. For each iteration, it constructs a verse of the song using string concatenation and logs it to the console.

2. Using a template literal and a while loop:

   let beer = 99;
   while (beer > 0) {
    let verse = `${beer} bottles of beer on the wall,
   ${beer} bottles of beer!
   Take one down, pass it around
   ${beer-1} bottles of beer on the wall`;
   
    console.log(verse);
    beer--;
   }

   This approach is similar to the previous one, but it uses a template literal to define the verse. Template literals provide a more concise syntax for multiline strings.

3. Using a function with a template literal and recursion:

   var bottles = 99;
   var songTemplate  = "{X} bottles of beer on the wall \n" +
                    "{X} bottles of beer \n"+
                    "Take one down, pass it around \n"+
                    "{X-1} bottles of beer on the wall \n";
   
   function song(x, txt) {
    return txt.replace(/\{X\}/gi, x).replace(/\{X-1\}/gi, x-1) + (x > 1 ? song(x-1, txt) : "");
   }
   
   console.log(song(bottles, songTemplate));

   This code defines a song template as a string with placeholders for the number of bottles. It then uses a recursive function called song to replace the placeholders and generate the lyrics for each verse. The result is logged to the console.

4. Using a while loop and document write:

   var beer; while ((beer = typeof beer === "undefined" ? 99 : beer) > 0) document.write( beer + " bottle" + (beer != 1 ? "s" : "") + " of beer on the wall<br>" + beer + " bottle" + (beer != 1 ? "s" : "") + " of beer<br>Take one down, pass it around<br>" + (--beer) + " bottle" + (beer != 1 ? "s" : "") + " of beer on the wall<br>" );

   This code uses a while loop to iterate from 99 down to 0. For each iteration, it generates a verse of the song as HTML and writes it to the document using the document.write function. This will display the lyrics on the web page.

5. Using Array.from and the forEach method:

   Array.from(Array(100).keys()).splice(1).reverse().forEach(n => console.log(`${n} bottle${n !== 1 ? 's' : ''} of beer on the wall\n${n} bottle${n !== 1 ? 's' : ''} of beer\nTake one down, pass it around\n${n - 1} bottle${n - 1 !== 1 ? 's' : ''} of beer on the wall\n\n`));

   This code uses Array.from to create an array of numbers from 1 to 99. It then uses splice, reverse, and forEach to iterate over the array from 99 down to 1, generating a verse of the song for each iteration.

6. Using a custom Bottles class:

   function Bottles(count) {
    this.count = count || 99;
   }
   
   Bottles.prototype.take = function() {
    var verse = [
      this.count + " bottles of beer on the wall,",
      this.count + " bottles of beer!",
      "Take one down, pass it around",  
      (this.count - 1) + " bottles of beer on the wall!"
    ].join("\n");
   
    console.log(verse);
   
    this.count--;
   };
   
   Bottles.prototype.sing = function() {
    while (this.count) { 
      this.take(); 
    }
   };
   
   var bar = new Bottles(99);
   bar.sing();

   This code defines a custom Bottles class that represents the state of the "bottles of beer" song. The constructor function takes an optional count argument, which defaults to 99. The class has two methods: take, which generates and logs a verse of the song while decrementing the count, and sing, which repeatedly calls take until the count reaches 0.

7. Using a function with a template literal and document manipulation:

   function bottleSong(n) {
    if (!isFinite(Number(n)) || n == 0) n = 100;
    var a  = '%% bottles of beer',
        b  = ' on the wall',
        c  = 'Take one down, pass it around',
        r  = '<br>'
        p  = document.createElement('p'),
        s  = [],
        re = /%%/g;
   
    while(n) {
      s.push((a+b+r+a+r+c+r).replace(re, n) + (a+b).replace(re, --n));
    }
    p.innerHTML = s.join(r+r);
    document.body.appendChild(p);
   }
   
   window.onload = bottleSong;

   This code defines a function called bottleSong that takes an optional integer argument. If the argument is not provided or is not a valid number, it defaults to 100. The function generates the lyrics of the song using a template literal and appends them to the document body as HTML. The window.onload event listener is used to call the function once the page has loaded.

var beer = 99;
while (beer > 0) {
  var verse = [
    beer + " bottles of beer on the wall,",
    beer + " bottles of beer!",
    "Take one down, pass it around",  
    (beer - 1) + " bottles of beer on the wall!"
  ].join("\n");

  console.log(verse);

  beer--;
}

let beer = 99;
while (beer > 0) {
  let verse = `${beer} bottles of beer on the wall,
  ${beer} bottles of beer!
  Take one down, pass it around
  ${beer-1} bottles of beer on the wall`;

  console.log(verse);
  beer--;
}

var bottles = 99;
var songTemplate  = "{X} bottles of beer on the wall \n" +
                    "{X} bottles of beer \n"+
                    "Take one down, pass it around \n"+
                    "{X-1} bottles of beer on the wall \n";

function song(x, txt) {
  return txt.replace(/\{X\}/gi, x).replace(/\{X-1\}/gi, x-1) + (x > 1 ? song(x-1, txt) : "");
}

console.log(song(bottles, songTemplate));

// Line breaks are in HTML
var beer; while ((beer = typeof beer === "undefined" ? 99 : beer) > 0) document.write( beer + " bottle" + (beer != 1 ? "s" : "") + " of beer on the wall<br>" + beer + " bottle" + (beer != 1 ? "s" : "") + " of beer<br>Take one down, pass it around<br>" + (--beer) + " bottle" + (beer != 1 ? "s" : "") + " of beer on the wall<br>" );

Array.from(Array(100).keys()).splice(1).reverse().forEach(n => console.log(`${n} bottle${n !== 1 ? 's' : ''} of beer on the wall\n${n} bottle${n !== 1 ? 's' : ''} of beer\nTake one down, pass it around\n${n - 1} bottle${n - 1 !== 1 ? 's' : ''} of beer on the wall\n\n`));

function Bottles(count) {
  this.count = count || 99;
}

Bottles.prototype.take = function() {
  var verse = [
    this.count + " bottles of beer on the wall,",
    this.count + " bottles of beer!",
    "Take one down, pass it around",  
    (this.count - 1) + " bottles of beer on the wall!"
  ].join("\n");

  console.log(verse);

  this.count--;
};

Bottles.prototype.sing = function() {
  while (this.count) { 
    this.take(); 
  }
};

var bar = new Bottles(99);
bar.sing();

function bottleSong(n) {
  if (!isFinite(Number(n)) || n == 0) n = 100;
  var a  = '%% bottles of beer',
      b  = ' on the wall',
      c  = 'Take one down, pass it around',
      r  = '<br>'
      p  = document.createElement('p'),
      s  = [],
      re = /%%/g;
  
  while(n) {
    s.push((a+b+r+a+r+c+r).replace(re, n) + (a+b).replace(re, --n));
  }
  p.innerHTML = s.join(r+r);
  document.body.appendChild(p);
}

window.onload = bottleSong;