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JavaScript : Convert a comma-separated values string to a 2D array of objects

JavaScript fundamental (ES6 Syntax): Exercise-4 with Solution

Write a JavaScript program to convert a comma-separated values (CSV) string to a 2D array of objects. The first row of the string is used as the title row.

  • Use Array.prototype.slice() and Array.prototype.indexOf('\n') and String.prototype.split(delimiter) to separate the first row (title row) into values.
  • Use String.prototype.split('\n') to create a string for each row, then Array.prototype.map() and String.prototype.split(delimiter) to separate the values in each row.
  • Use Array.prototype.reduce() to create an object for each row's values, with the keys parsed from the title row.
  • Omit the second argument, delimiter, to use a default delimiter of ,.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2
const CSV_to_JSON = (data, delimiter = ',') => {
  const titles = data.slice(0, data.indexOf('\n')).split(delimiter);
  return data
    .slice(data.indexOf('\n') + 1)
    .split('\n')
    .map(v => {
      const values = v.split(delimiter);
      return titles.reduce((obj, title, index) => ((obj[title] = values[index]), obj), {});
    });
};
console.log(CSV_to_JSON('col1,col2\na,b\nc,d')); // [{'col1': 'a', 'col2': 'b'}, {'col1': 'c', 'col2': 'd'}];
console.log(CSV_to_JSON('col1;col2\na;b\nc;d', ';')); // [{'col1': 'a', 'col2': 'b'}, {'col1': 'c', 'col2': 'd'}];

Sample Output:

[{"col1":"a","col2":"b"},{"col1":"c","col2":"d"}]
[{"col1":"a","col2":"b"},{"col1":"c","col2":"d"}]

Flowchart:

flowchart: Convert a comma-separated values string to a 2D array of objects

Live Demo:

See the Pen javascript-basic-exercise-1-4 by w3resource (@w3resource) on CodePen.


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Next: Write a JavaScript program to convert an array of objects to a comma-separated values (CSV) string that contains only the columns specified.

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JavaScript: Tips of the Day

Chunks an array into n smaller arrays

Example:

const tips_chunkIntoN = (arr, n) => {
  const size = Math.ceil(arr.length / n);
  return Array.from({ length: n }, (v, i) =>
    arr.slice(i * size, i * size + size)
  );
}
console.log(tips_chunkIntoN([1, 2, 3, 4, 5, 6, 7,8], 4)); 

Output:

[[1,2],[3,4],[5,6],[7,8]]