This is probably very trivial but I can't for the life of me find any good documentation. I have an AJAX event setup where I need to send a timestamp from the client side to the server. The server script (PHP) will check the timestamp that it has been passed, against a CURRENT_TIMESTAMP in a mysql table and act upon the results.
My problem is that I need to create a timestamp in JavaScript on the client page that will be comparable to the mysql timestamp.
Alex almost had it
The only thing that is wrong is that JS timestamps are in milliseconds and UNIX timestamps are in seconds. Therefore you need to divide the JS timestamp by 1000.
var unixNow = Math.round( (new Date().getTime()) / 1000);
How about just sending seconds from Epoch from JavaScript...
var secondsFromEpoch = ~~(+new Date / 1000);
..and then change your query to...
WHERE UNIX_TIMESTAMP(`datetime`) == :secondsFromEpoch_passed_from_JavaScript
?
+ new Date is the same as new Date().getTime() the + converts the date to a number. The ~~ is another way to implement Math.round(), I've heard it's even faster+ calls the Date's valueOf() which returns a Number. Secondly, ~~, or double invert bits, is functionally the same as Math.floor().+ before a date converts it to a number of milliseconds, you just added that it's because it calls valueOf(). Secondly ~~ is not the same as Math.floor either, so we were both wrong. Math.floor(-8.3) == -9 and ~~(-8.3) == -8. Therefore, it's the same as Math.floor for positive numbers and Math.ceil for negative numbers. So I don't think it's a very good idea, since you'd have different behavior for dates before and after 1970.Number a good way to work with pre 1970 dates? That's a question in itself I guess...