csv-tools/lib/fromJSON.ts

Convert CSV to JSON and JSON to CSV.

export function jsonArrayToCsv(jsonArray: any[], delimiter: string = ','): string {
  if (!jsonArray || jsonArray.length <= 0)
    throw new Error("The array must contain at least one JSON object");

  const data: any[] = [];
  const headers = [];
  for (const i in jsonArray) {
    const jsonObject = jsonArray[i];
    data[i] = [];
    for (const prop in jsonObject) {
      const headerArray: string[] = [];
      propToHeader(jsonObject[prop], prop, headerArray, data[i]);
      for (const j in headerArray) {
        const header = headerArray[j];
        if (headers.indexOf(header) == -1)
          headers.push(header);
      }
    }
  }

  let result = headers.map(item => `"${item}"`).join(delimiter) + "\n";
  for (let z = 0; z < data.length; z++) {
    let row = "";
    for (let k = 0; k < headers.length; k++) {
      const key = headers[k];
      let value = data[z][key];
      if (k > 0)
        row += delimiter;
      if (value !== undefined && value !== null) {
        if (typeof value == "string") {
          value = value.replace(/"/g, '""');
          value = `"${value}"`;
        }
        row += value;
      }
    }
    result += row;
    if (z < data.length - 1)
      result += "\n";
  }

  return result;
}

function propToHeader(jsonObject: any, parents: string, headerArray: string[], dataArray: any) {
  if (typeof jsonObject !== "object") {
    headerArray.push(parents);
    dataArray[parents] = jsonObject;
  } else {
    for (const p in jsonObject) {
      propToHeader(jsonObject[p], `${parents}.${p}`, headerArray, dataArray);
    }
  }
}