SSJS Lyric Parser for Salesforce Marketing Cloud

I recently participated in a contest organised by the HowToSFMC community, where contestants had to display the lyrics of the song 'One More Time' using Server-Side JavaScript (SSJS) in Salesforce Marketing Cloud, in an efficient manner.

Approach

My initial observation was that while the chorus and bridge in the lyrics are short and repetitive, but they follow an irregular pattern.

To present the lyrics in a manner that they could be reconstructed, I firstly identified distinct lines in the lyrics and stored them in an array—arrays are a great fit for this task, as they provide a very convenient method of storing multiple values in a single variable.

var lyrics = [
   "One more time",
   "We're gonna celebrate",
   "Oh yeah, all right",
   "Don't stop the dancing",
   "Oh yeah",
   "Mmm, you know I'm just feeling",
   "Celebration tonight",
   "Celebrate",
   "Don't wait too late",
   "Mmm, no",
   "We don't stop",
   "You can't stop",
   "Celebration",
   "You know we're gonna do it right, tonight",
   "Hey! Just feeling",
   "Music's got me feeling the need",
   "Need, yeah",
   "Come on, all right",
   "Celebrate and dance so free",
   "Music's got me feeling so free"
]

My next task was to reassemble these distinct lines back to their original order. The simple option would have been to create a separate array of indices from the first array and then output them. For example, the following lyrics:

One more time
Music’s got me feeling so free
We’re gonna celebrate

…could be stored in an array based on their zero-based index in the lyrics array. Then this array could be looped to retrieve the corresponding line and output with a line break, like the following example:

var order = [0, 19, 1]

for (var i = 0; i < order.length; i++) {
  Write(lyrics[order[i]] + '\n');
}

While this is simple, the issue is that there are a total of 112 lines (excluding paragraph breaks), which would require a very long array of indices. However, from studying the lyric patterns, I observed two pattern formations:

1. A repeat pattern, where a set of lines were repeated two or more times, and
2. An increment pattern, where a set of lines in the lyrics array appeared consecutively.

To take advantage of these patterns, I optimized my code by creating separate functions to parse each pattern.

Repeat Function

To display repeating lines, I created a repeat function which accepts three arguments:

1. An array of line indices (of the lyrics array) represented by the arr parameter,
2. The number of times to repeat the lines represented by the count parameter, and
3. An optional integer that inserts a line break after a section of repeated lines represented by the line parameter.

The function is provided below.

function repeat(arr, count, line) {
   for (i = 0; i < count; i++) {
      for (j = 0; j < arr.length; j++) {
         order.push(arr[j]);
      }
      if (line === i + 1) {
         order.push(-1);
      }
   }
}

If the line parameter is included, then a -1 index is appended to the array which will insert a line break (refer to my explanation of the output function). As arrays in JavaScript are zero based, I included an addition operator (+) to add a value of 1 to the evaluated expression condition, largely for readability (to indicate after which line set the paragraph break should appear).

For example, the following code:

repeat([0, 19, 1, 18], 6, 2);

…will repeat lines 0, 19, 1 and 18 from the lyrics index, six times. Additionally, a paragraph break will be inserted after the second line set, resulting in the following output:

One more time
Music’s got me feeling so free
We’re gonna celebrate
Celebrate and dance so free // end of 1st line set
One more time
Music’s got me feeling so free
We’re gonna celebrate
Celebrate and dance so free // end of 2nd line set
// line break inserted here
One more time
Music’s got me feeling so free
We’re gonna celebrate
Celebrate and dance so free // end of 3rd line set
…
One more time
Music’s got me feeling so free
We’re gonna celebrate
Celebrate and dance so free // end of 6th line set

When the function is invoked, the resulting indices are appended to the order array using the JavaScript push() method.

Increment Function

The increment function accepts two arguments:

1. A start index number (from the lyrics array), and
2. An end index number.

The function is provided below.

function increment(start, end) {
   for (i = start; i < end + 1; i++) {
      order.push(i);
   }
}

When the function is invoked, the corresponding indices are appended to the order array using the JavaScript push() method. For example, the following code:

increment(5, 11)

…will return lines 5–11 from the lyrics index, resulting in the following output:

Mmm, you know I’m just feeling
Celebration tonight
Celebrate
Don’t wait too late
Mmm, no
We don’t stop
You can’t stop

Output Function

The final task is to output the lines from the lyrics array in the order that they appear in the order array.

To achieve this, an empty result array is defined to store the resulting strings. The function accepts a single arr parameter (with the array of line indices), and adds each line to the result array using the JavaScript push() method.

The function is provided below.

function output(arr) {
   var result = [];
   for (i = 0; i < arr.length; i++) {
      result.push(lyrics[arr[i]]);
   }
   return result.join('\n');
}

The result array now contains an ordered array of lines to display. For example, including Write(Stringify(result)) in the function will return the following output:

["One more time",
"One more time",
null,
"One more time",
"We're gonna celebrate",
"Oh yeah, all right",
...
"Music's got me feeling so free",
"We're gonna celebrate",
"Celebrate and dance so free"]

Note that where paragraph breaks are required, the index value was defined as -1 which returns a null value (as there is no matching index in the lyrics array).

The final step is to join the values in the array and insert line breaks between each value. The JavaScript join() method converts the values of the array into a string. Additionally, a separator parameter is passed to the array to separate each line with a new line character (\n). And for paragraph breaks (indicated by an array value of null), this results in two consecutive line break characters (\n\n), to form a paragraph break.

Finally, the function is invoked by the following code, which retrieves the resulting string from the output() function and uses the Write utility function (provided by the SSJS Core Library) to output the resulting lyrics in the correct order.

Write(output(order));

Learnings

While this script doesn’t have any practical context (I doubt that I'll ever need to output song lyrics!), it was very helpful in creating a solution to parse datasets that contain similar characteristics, then process them in an optimal way. I look forward to applying this pattern to future projects!

Script

The complete SSJS code is provided here.