Split a markdown without breaking a code block

split-markdown.util.ts

function splitMarkdown(str: string, limit: number): string[] {
  return str.match(new RegExp(`.*([^]){1,${limit}}(\n)?$`, 'gm')).reduce((acc, curr) => {

    const lastValue = acc.at(-1);
    if (!lastValue) return [curr];

    
    const heads = lastValue.match(/```.*/g) as string[] || [];

    // If the number of heads is even or 0, then all code blocks are closed
    const isCodeBlockClosed = (heads.length % 2 === 0) || !heads.length;

    
    return [

      // We are updating the last value, so we slice the accumulator
      ...acc.slice(0, -1),

      // If the code block is not closed, then close it
      isCodeBlockClosed ? lastValue : lastValue + '\n```',

      // And open it with the same last open head
      isCodeBlockClosed ? curr : heads.at(-1) + '\n' + curr
    ];

  }, []);
}