Following is an example on how can we use Regular Expression to parse a CSV file in Java script

function CSVToArray( strData, strDelimiter ){
	// Check to see if the delimiter is defined. If not,
	// then default to comma.
	strDelimiter = (strDelimiter || ",");

	// Create a regular expression to parse the CSV values.
	var objPattern = new RegExp(
		(
			// Delimiters.
			"(\\" + strDelimiter + "|\\r?\\n|\\r|^)" +

			// Quoted fields.
			"(?:\"([^\"]*(?:\"\"[^\"]*)*)\"|" +

			// Standard fields.
			"([^\"\\" + strDelimiter + "\\r\\n]*))"
		),
		"gi"
		);


	// Create an array to hold our data. Give the array
	// a default empty first row.
	var arrData = [[]];

	// Create an array to hold our individual pattern
	// matching groups.
	var arrMatches = null;


	// Keep looping over the regular expression matches
	// until we can no longer find a match.
	while (arrMatches = objPattern.exec( strData )){

		// Get the delimiter that was found.
		var strMatchedDelimiter = arrMatches[ 1 ];

		// Check to see if the given delimiter has a length
		// (is not the start of string) and if it matches
		// field delimiter. If id does not, then we know
		// that this delimiter is a row delimiter.
		if (
			strMatchedDelimiter.length &&
			strMatchedDelimiter !== strDelimiter
			){

			// Since we have reached a new row of data,
			// add an empty row to our data array.
			arrData.push( [] );

		}

		var strMatchedValue;

		// Now that we have our delimiter out of the way,
		// let's check to see which kind of value we
		// captured (quoted or unquoted).
		if (arrMatches[ 2 ]){

			// We found a quoted value. When we capture
			// this value, unescape any double quotes.
			strMatchedValue = arrMatches[ 2 ].replace(
				new RegExp( "\"\"", "g" ),
				"\""
				);

		} else {

			// We found a non-quoted value.
			strMatchedValue = arrMatches[ 3 ];

		}


		// Now that we have our value string, let's add
		// it to the data array.
		arrData[ arrData.length - 1 ].push( strMatchedValue );
	}

	// Return the parsed data.
	return( arrData );
}