How to identify the use of Ajax in jQuery?

I want to make a form that uses jQuery's ajax function to submit the data, but to be functional when javascript is disabled. So I need a way to know, in the server-side script (PHP), weather the request came from ajax or from simply submiting the form.

HTML:

<form id="form_1" method=开发者_运维问答"post" action="process.php">

jQuery:

$.ajax({
        type: "POST",
        url: "process.php",
        data: $("#form_1").serialize(),
        cache: false,
        success: function(msg){alert(msg)}
    });

So I would like to check in process.php if it was called from jQuery or from submiting the form. Note that I serialize the data, I don't want to use an URL parameter, like '&ajax=1'. Thanks!

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Automatically, requests made with XMLHTTPRequest (like those made with jQuery's AJAX suite) have the X-Requested-With header set to XMLHTTPRequest. You can check for the presence of this header.

if (
    isset($_SERVER['HTTP_X_REQUESTED_WITH']) && 
    ($_SERVER['HTTP_X_REQUESTED_WITH'] === 'XMLHTTPRequest')
) {
    // request is AJAX
}

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You can check for the presence of $_SERVER['HTTP_X_REQUESTED_WITH']. jQuery will send this header with AJAX calls.

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The jQuery serialize() method won't serialize (and therefore provide a value for) any submit buttons contained within the form, but submitting the form using one of these will do so. You can check for the existence of that value using PHP and handle appropriately.

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I know you don't want to use a url parameter, but it might be the only way you can determine where the call came from.

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You can construct data manually and add an AJAX only parameter, and then check for it in PHP.

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I would suggest you add a field to your form when it is submited via ajax just before the ajax call. So you can serialize your form and send it as the data containing your ajax=1 for example

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The server has no guaranteed way to know what mechanism the client used to make a request. Any request that you can make via JQuery or any other kind of page load can be spoofed by another client to look exactly the same; the server would have no clue.

A client that isn't trying to spoof the result will generally send some clues to the server, in the form of the UserAgent string, and so on, but none of these clues will tell the server anything about whether it's being called via Ajax or not.

Therefore the only route you have to tell the server where the request is coming from is in the URL, and the easiest way to do that is to add an extra parameter. I know you don't want to do this, but it is the best answer to your question.

The alternative option is to have a different action URL for the form if it is called via Javascript. You can toggle the URL easily in JQuery when the page is loaded, and because it is done in Javascript, if JS is disabled then the form will post to the default URL, and you'll be able to generate you non-JS page load.

The final solution is not to do anything different on the server; render the page exactly the same whichever route the user comes in via, and instead have the JQuery code accept the that page code and extract the relevant parts of it for use in the Ajax context.

I hope that helps.

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There is a much simpler way to achieve this. Use something similar for jQuery:

$("form").submit(function(){ /*ajax request*/ return false; }

The return false; does the "magic". If you have JS enabled, then the submit button won't submit the regular way; you can process data via jQuery and send it with AJAX. If you have JS disabled, therefore this function is not called and the form is submitted as usual.