bigcapital/client/src/lang/printValue.js

const toString = Object.prototype.toString;
const errorToString = Error.prototype.toString;
const regExpToString = RegExp.prototype.toString;
const symbolToString =
  typeof Symbol !== 'undefined' ? Symbol.prototype.toString : () => '';
const SYMBOL_REGEXP = /^Symbol\((.*)\)(.*)$/;

function printNumber(val) {
  if (val !== +val) return 'NaN';
  const isNegativeZero = val === 0 && 1 / val < 0;
  return isNegativeZero ? '-0' : '' + val;
}

function printSimpleValue(val, quoteStrings = false) {
  if (val == null || val === true || val === false) return '' + val;

  const typeOf = typeof val;
  if (typeOf === 'number') return printNumber(val);
  if (typeOf === 'string') return quoteStrings ? `"${val}"` : val;
  if (typeOf === 'function')
    return '[Function ' + (val.name || 'anonymous') + ']';
  if (typeOf === 'symbol')
    return symbolToString.call(val).replace(SYMBOL_REGEXP, 'Symbol($1)');

  const tag = toString.call(val).slice(8, -1);
  if (tag === 'Date')
    return isNaN(val.getTime()) ? '' + val : val.toISOString(val);
  if (tag === 'Error' || val instanceof Error)
    return '[' + errorToString.call(val) + ']';
  if (tag === 'RegExp') return regExpToString.call(val);

  return null;
}

export default function printValue(value, quoteStrings) {
  let result = printSimpleValue(value, quoteStrings);
  if (result !== null) return result;

  return JSON.stringify(
    value,
    function(key, value) {
      let result = printSimpleValue(this[key], quoteStrings);
      if (result !== null) return result;
      return value;
    },
    2,
  );
}