Type utility in JS.

typeUtil.js

const getTypeName = (o) => {
  if (o === undefined) return 'undefined';
  if (o === null) return 'null';
  return o.constructor.name;
};

const isUndefined = (o) => (o === undefined);

const isNull = (o) => (o === null);

const isString = (o) => (getTypeName(o) === 'String');

const isNumber = (o) => (getTypeName(o) === 'Number');

const isInteger = (o) => (Number.isInteger(o));

const isBoolean = (o) => (getTypeName(o) === 'Boolean');

const isArray = (o) => (Array.isArray(o));

const isPureObject = (o) => (getTypeName(o) === 'Object');

const isSymbol = (o) => (getTypeName(o) === 'Symbol');

export default {
  getTypeName,
  isUndefined,
  isNull,
  isString,
  isNumber,
  isInteger,
  isBoolean,
  isArray,
  isPureObject,
  isSymbol,
};