Commonly used Javascript snippet

javascript.js

function jsonStr(obj, indent) {
  return JSON.stringify(
    obj, 
    // default result of JSON.stringify() for RegExp object is {}
    (key, value)=> {
      if (value instanceof RegExp) {
        return value.toString(); // RegExp.toString() returns string like '/\\.(t|j)sx?$/'
      }
      return value;
    },
    // to output a formatted JSON, use the 3rd parameter of JSON.stringify for indenting, usually some spaces or '\t'.
    indent ? ' '.repeat(indent) : '');
}

function isRegExp(obj) {
  return obj instanceof RegExp;
}