Get time of page loading start in JavaScript

Question

In JavaScript it is possible to wait for onLoad which may be used to specify the time of page loading completion.

Every HTTP response is sent along with Date: header which contains the time server sent a response.

Is there a way in JavaScript to get the time of page started loading? Something similar to response Date: header.

It would be useful for cases when JavaScript is injected into page after some delay.

The server can write the time into the response in a number of ways: JavaScript code, HTML attribute values, etc. — Pointy, Jul 02 '12 at 14:59

score 9 · Accepted Answer · edited May 06 '20 at 09:06

9

new Date(performance.timing.connectStart) in chrome, firefox, IE9, etc (caniuse)

demo

console.log(new Date(performance.timing.connectStart));

edited May 06 '20 at 09:06

Flimm

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answered Jul 02 '12 at 15:00

Esailija

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As a side bonus I learned that: *The window.performance.navigation object stores two attributes that can be used to know if a page load is triggered by a redirect, back/forward button or normal URL load.* – Esailija Jul 02 '12 at 15:12

score 1 · Answer 2 · answered Jul 02 '12 at 15:01

1

Try storing a value from var d= new Date(); var requested = d.getTime(); and execute it when the page loads.

answered Jul 02 '12 at 15:01

Polyov

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score 0 · Answer 3 · answered Jul 02 '12 at 15:08

<!DOCTYPE html>
<html>
<head>
    <title></title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <script type="text/javascript">
        var loadDate;
    </script>
</head>
<body onload="loadDate=new Date();">
    <button onclick="alert(loadDate);">show load Date</button>
</body>
</html>

score 0 · Answer 4 · answered Jul 10 '23 at 09:33

Update 2023

As performance.timing.connectStart is deprecated, I recommend:

window.performance?.timeOrigin

Here is my code to get something bullet-proof:

    const sessionStartDateTime = window.performance?.timeOrigin ?? window.performance?.timing?.connectStart ?? Date.now();

Sources:

Hope ir helps :)

score -1 · Answer 5 · answered Jul 02 '12 at 15:06

-1

I would just pass a timestamp from the server-side script to the browser via a cookie or inline JS. E.g. in PHP:

<script>
var timestamp = new Date(<?php echo time(); ?>);
</script>

answered Jul 02 '12 at 15:06

Lèse majesté

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Get time of page loading start in JavaScript

5 Answers5

Update 2023