index.js

'use strict';

var strValue = String.prototype.valueOf;
var tryStringObject = function tryStringObject(value) {
	try {
		strValue.call(value);
		return true;
	} catch (e) {
		return false;
	}
};
var toStr = Object.prototype.toString;
var strClass = '[object String]';
var hasToStringTag = typeof Symbol === 'function' && typeof Symbol.toStringTag === 'symbol';

module.exports = function isString(value) {
	if (typeof value === 'string') {
		return true;
	}
	if (typeof value !== 'object') {
		return false;
	}
	return hasToStringTag ? tryStringObject(value) : toStr.call(value) === strClass;
};