How to Submit Forms in Background using JavaScript

H
Published in: JavaScript

When a user submits an HTML form, all the data entered into the form by the user is sent as either a GET or POST request to the URL specified in the “ACTION” attribute of FORM.

 <FORM action="http://www.labnol.org/sendmail.php" method="post">
 ...form contents...
 </FORM>

In the above example, an HTTP POST request is issued to the sendmail.php script on form submission. You can add target=“_blank” to the FORM tag to process the request in a new window.

However, if you would like to submit a FORM on the page in the background without directing the browser to another page (document.location.href changes on form submit), you have two options:

Option #1. You can either create an invisible IFRAME inside your HTML page and set that as a target for the Original FORM. This will submit the form but without reloading the parent window.

 <FORM action="http://example.com/script.php"
           method="POST" target="hidden-form">
 ...form contents...
 </FORM>
<IFRAME style="display:none" name="hidden-form"></IFRAME>

Option #2: There’s another method that allows you create custom payloads before submitting the form. Unlike the IFRAME based form submission, the following code makes a standard form submit request and thus your browser location will change and the current page will get added to the browser history.

submitFORM('http://example.com/script.php', 'POST',
    {'name':'digital+inspiration', 'age':'100', 'sex','M'});

function submitFORM(path, params, method) {
    method = method || "post";

    var form = document.createElement("form");
    form.setAttribute("method", method);
    form.setAttribute("action", path);

    //Move the submit function to another variable
    //so that it doesn't get overwritten.
    form._submit_function_ = form.submit;

    for(var key in params) {
        if(params.hasOwnProperty(key)) {
            var hiddenField = document.createElement("input");
            hiddenField.setAttribute("type", "hidden");
            hiddenField.setAttribute("name", key);
            hiddenField.setAttribute("value", params[key]);

            form.appendChild(hiddenField);
         }
    }

    document.body.appendChild(form);
    form._submit_function_();
}
Published in: JavaScript

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Web Geek, Tech Columnist
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Amit Agarwal

Amit Agarwal is a Google Developer Expert in GSuite and Google Apps Script. He holds an engineering degree in Computer Science (I.I.T.) and is the first professional blogger in India. Read more on Lifehacker and YourStory

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