make a string .toISOString is not a function code example
Example: date.toisostring is not a function
Date.now() returns a number which represents the number of milliseconds elapsed since the UNIX epoch. The toISOString method cannot be called on a number, but only on a Date object, like this:
var now = new Date();
var isoString = now.toISOString();
Or in one single line:
new Date().toISOString()