How to convert JSON to CSV format and store in a variable

Question

I have a link that opens up JSON data in the browser, but unfortunately I have no clue how to read it. Is there a way to convert this data using JavaScript in CSV format and

Answer 1

Sometimes objects have different lengths. So I ran into the same problem as Kyle Pennell. But instead of sorting the array we simply traverse over it and pick the longest. Time complexity is reduced to O(n), compared to O(n log(n)) when sorting first.

I started with the code from Christian Landgren's updated ES6 (2016) version.

json2csv(json) {
    // you can skip this step if your input is a proper array anyways:
    const simpleArray = JSON.parse(json)
    // in array look for the object with most keys to use as header
    const header = simpleArray.map((x) => Object.keys(x))
      .reduce((acc, cur) => (acc.length > cur.length ? acc : cur), []);

    // specify how you want to handle null values here
    const replacer = (key, value) => (
      value === undefined || value === null ? '' : value);
    let csv = simpleArray.map((row) => header.map(
      (fieldName) => JSON.stringify(row[fieldName], replacer)).join(','));
    csv = [header.join(','), ...csv];
    return csv.join('\r\n');
}