This JavaScript function processes long text inputs by breaking them into smaller chunks, applying a custom processing function to each chunk, and optionally handling overlaps between chunks.

processTextInChunks(inputText, processFn, config)

• inputText (string): The long input text to be processed.
• processFn (function, optional): A function to process each chunk. Defaults to logging the chunk.
• config (object, optional): Configuration options.

• chunkLength (number): Length of each chunk. Default: 1000.
• overlapLength (number): Length of overlap between chunks. Default: 0.

const longText = "Your very long text here...";

const result = processTextInChunks(longText, 
  (mainChunk, overlapChunk, info) => {
    // Process the chunk here
    console.log(`Processing chunk from ${info.startIndex} to ${info.endIndex}`);
    console.log(`Main chunk: ${mainChunk}`);
    console.log(`Overlap: ${overlapChunk}`);
    return mainChunk.length; // Example return value
  }, 
  {
    chunkLength: 500,
    overlapLength: 50
  }
);

console.log(result);

• If processFn is not provided, the function will log each chunk and return the original text.
• If processFn returns a value, these values will be collected in an array and returned.
• If processFn doesn't return anything, the original input text is returned.
• The processFn receives three arguments:
  1. mainChunk: The current chunk of text being processed.
  2. overlapChunk: The overlapping text from the previous chunk (empty for the first chunk).
  3. An info object containing:
     • startIndex: Start index of the current chunk in the original text.
     • endIndex: End index of the current chunk in the original text.
     • isLastChunk: Boolean indicating if this is the last chunk.

• Processing large texts in smaller, manageable pieces.
• Applying transformations or analysis to text while maintaining context through overlaps.
• Tokenization or parsing of large documents.