how does javascript get accurate date and time code example

Example 1: how to get timestamp in javascript of a date object

new Date().getTime()

new Date().valueOf()

Example 2: javascript current date time

var today = new Date().toLocaleDateString(undefined, {
    day: '2-digit',
    month: '2-digit',
    year: 'numeric',
    hour: '2-digit',
    minute: '2-digit',
    second: '2-digit'
})