The value to get the string representation for. 要获取字符串表示的值
The string representation of the value. 值的字符串表示
toString(42) // => '42'
toString('hello') // => 'hello'
toString(undefined) // => 'undefined'
toString(null) // => 'null'
toString({}) // => '[object Object]'
Get the string representation of a value
获取值的字符串表示