autocast.js

/*
These codes is borrowed from
https://github.com/mholt/PapaParse/blob/master/papaparse.js
 */

const MAX_FLOAT = Math.pow(2, 53);
const MIN_FLOAT = -MAX_FLOAT;
const FLOAT = /^\s*-?(\d+\.?|\.\d+|\d+\.\d+)(e[-+]?\d+)?\s*$/;
const ISO_DATE = /(\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d\.\d+([+-][0-2]\d:[0-5]\d|Z))|(\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d([+-][0-2]\d:[0-5]\d|Z))|(\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d([+-][0-2]\d:[0-5]\d|Z))/;

function autoCast(value) {
  if (value === 'true' || value === 'TRUE')
    return true;
  else if (value === 'false' || value === 'FALSE')
    return false;
  else if (testFloat(value))
    return parseFloat(value);
  else if (ISO_DATE.test(value))
    return new Date(value);
  else
    return (value === '' ? undefined : value);
}

function testFloat(s) {
  if (FLOAT.test(s)) {
    const floatValue = parseFloat(s);
    if (floatValue > MIN_FLOAT && floatValue < MAX_FLOAT) {
      return true;
    }
  }
  return false;
}

module.exports = autoCast;