toString

undefined.toString()   // 报错  Cannot read property 'toString' of undefined
null.toString()  // 报错  Cannot read property 'toString' of null
new Date().toString() //"Tue Jun 28 2022 13:38:30 GMT+0800 (中国标准时间)"
123.toString() // 报错  Invalid or unexpected token
'124'.toString() // 123
[].toString() // ''
[1,2,3].toString() // 1,2,3
{}.toString() //报错
{name:111}.toString() // 报错  Unexpected token '.'
true.toString() // true
new Boolean().toString(); // false