Create an array of weeks with start and end week date from a given start date to today. No external libraries.

weekArray.js

// Add 0 to date value smaller than 10. For example, date 8 of July will become 07-08.
function padDate(number) {
  return number < 10 ? '0' + number.toString() : number.toString();
}
// format the date object as YYYY-MM-DD
function formatDate(date) {
  const yr = date.getFullYear();
  const mo = padDate(date.getMonth() + 1);
  const da = padDate(date.getDate());
  return `${yr}-${mo}-${da}`;
}

function getWeekArray(givenDate) {
  // turn the startDate into a Date object
  const given = new Date(givenDate);
  const givenCp = new Date(given);
  // Find the number that we have to subtract from the start date to arrive at the previous Monday
  const offset = (given.getDay() + 6) % 7;
  // Get the Monday in the same week as the start date in milliseconds
  const earliestMonInMillisecs = givenCp.setDate(givenCp.getDate() - offset)
  const earliestMon = new Date(earliestMonInMillisecs);
  console.log('earliest mon is ', earliestMon);
  let weeks = [];
  // Save the earliest Monday to a new temporary variable 
  let start = new Date(earliestMon);
  let _start = new Date(start);
  let sun = new Date(_start.setDate(_start.getDate() + 6));
  console.log(sun);
  const now = new Date();
  while (sun < now) {
    const from = formatDate(start);
    const to = formatDate(sun);
    weeks.push({from, to});
    start = new Date(start.setDate(start.getDate() + 7));
    sun = new Date(sun.setDate(sun.getDate() + 7));
    console.log('next sun is ', sun);
  }
  console.log('given date is ', given);
  return weeks;
}

console.log(getWeekArray('2020-07-06T13:22:09.000Z'));