interlace.ts

export function interlace(array: any[], joiner: any): any[] {
  const result: any[] = [];
  if (!array || !array.length) {
    return result;
  }

  let i;
  for (i = 0; i < array.length - 1; i++) {
    result.push(array[i]);
    result.push(joiner);
  }
  result.push(array[i]);
  return result;
}

export function ander(strings: string[]): string {
  if (!strings || !strings.length) {
    return '';
  }
  if (strings.length === 1) {
    return strings[0];
  }
  if (strings.length === 2) {
    return `${strings[0]} and ${strings[1]}`;
  }
  strings[strings.length - 1] = `and ${strings[strings.length - 1]}`;
  return strings.join(', ');
}

export function sentenceCase(paragraph: string) {
  if (!paragraph) {
    return;
  }
  return paragraph
    .split('. ')
    .map(sentence => `${sentence[0].toUpperCase()}${sentence.substring(1)}`)
    .join('. ');
}