For frontend related concepts, try: https://youtube.com/devtoolstech/videos

One possible implementation could be:

function multiple(position) {
  // write your code below

  const length = this.length;
  
  // length valid check
  if (length === 0) {
    return 0;
  }

  const collection = [];

  for (let i = 0; i &lt; length; i++) {
    const current = this[i];
    const actualPosition = position - 1;

    // checking if the position exists in the array
    if (Object.prototype.hasOwnProperty.call(current, actualPosition)) {
      collection.push(current[actualPosition]);
    }
  }

  // length valid check
  if (!collection.length) {
    return 0;
  }

  // multiplication progressing
  return collection.reduce((r, j) =&gt; r * j, 1);
}

function tuple(input) {
  // write your code below

  // checking the typeof the input
  if (typeof input !== 'string') {
    throw new TypeError('Invalid params');
  }

  // return empty array if the input is invalid
  if (input &amp;&amp; !input.trim().length) {
    return [];
  }

  // finding different groups
  // (1,2,3) (4,5,6) (7,8,9)
  const matchedGroups = input.match(/(\([^\)]+\)?)/g);
  
  // escape condition
  if (!matchedGroups) {
    return [];
  }

  const result = matchedGroups.reduce((rows, group) =&gt; {
    // sanitize group
    let row = group.replace(/[\(\)\s]/g, '').split(',');
    
    // parse elements to group
    row = row.map((el) =&gt; Number(el));

    rows.push(row);

    return rows;
  }, []);

  return result;
}

Array.prototype.multiple = multiple;

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Implement Tuple Function | LinkedIn Frontend Interview Question | JavaScript Problem Solving

@Kanishk Chowdhury