Javascript get form data

Javascript wears many hats. You can use JavaScript to create special effects. This last application is of particular importance. Of all the hats JavaScript can wear, its form processing features are among the most sought and used. Nothing strikes more fear in the heart of a Web publisher than these three letters: C-G-I. CGI which stands for common gateway interfaceis a mechanism for safely transporting data from a client a browser to a server.

It is typically used to transfer data from an HTML form to the server. With JavaScript at your side, you can process simple forms without invoking the server. And when submitting the form to a CGI program is necessary, you can have JavaScript take care of all the preliminary requirements, such as validating input to ensure that the user has dotted every i.

In this column we'll look closely at the JavaScript-form connection, including how to use JavaScript's form object, how to read and set form content, and how to trigger JavaScript events by manipulating form controls.

javascript get form data

This article is part of the JavaWorld technical content archive. You can learn a lot about JavaScript programming by reading articles in the JavaScript seriesjust keep in mind that some of the information is likely to be outdated.

javascript get form data

The main one being that a JavaScript form relies on one or more event handlers, such as onClick or onSubmit. These invoke a JavaScript action when the user does something in the form, like clicking a button. The event handlers, which are placed with the rest of the attributes in the HTML form tags, are invisible to a browser that don't support JavaScript.

Because of this trait, you can often use one form for both JavaScript and non-JavaScript browsers. I won't bother enumerating all the attributes of these controls widgetsand how to use them in HTML. Most any reference on HTML will provide you with the details.

For use with JavaScript, you should always remember to provide a name for the form itself, and each control you use. The names allow you to reference the object in your JavaScript-enhanced page.

The typical form looks like this. Let's experiment with obtaining values from form objects. Load the page, then type something into the text box. Click the button, and what you typed is shown in the alert box.Help to translate the content of this tutorial to your language! This chapter is about sending HTML forms: with or without files, with additional fields and so on.

FormData objects can help with that. The special thing about FormData is that network methods, such as fetchcan accept a FormData object as a body. A form is technically allowed to have many fields with the same nameso multiple calls to append add more same-named fields. The difference is that. We can supply it directly as fetch parameter body. Also, servers are usually more suited to accept multipart-encoded forms, rather than raw binary data.

We can either create new FormData form from an HTML form, or create a object without a form at all, and then append fields with methods:. We want to make this open-source project available for people all around the world. Tutorial map. Previous lesson Next lesson. Comments read this before commenting… If you have suggestions what to improve - please submit a GitHub issue or a pull request instead of commenting.

If you can't understand something in the article — please elaborate. Chapter Network requests. Edit on GitHub.This article explores such approaches. With progressive web apps, single page apps, and framework based apps, it's common to use HTML forms to send data without loading a new document when response data is received.

Let's first talk about why this requires a different approach. Standard HTML form submission, as described in the previous article, loads the URL where the data was sent, which means the browser window navigates with a full page load. Avoiding a full page load can provide a smoother experience by avoiding network lag, and possible visual issues like flickering. When the user tries to send the data, the application takes control and transmits the data asynchronously in the background, updating only the parts of the UI that require changes.

Most of the XHR code you'll see in this article could be swapped out for Fetch.

javascript get form data

But if you want to use a third party service, you need to send the data in the format the services require. There are 3 ways to send form data, from legacy techniques to the newer FormData object. Let's look at them in detail. Note: This use of XMLHttpRequest is subject to the same-origin policy if you want to send data to a third party web site.

Building an HTTP request by hand can be overwhelming. The FormData object can be used to build form data for transmission, or to get the data within a form element to manage how it's sent.

Note that FormData objects are "write only", which means you can change them, but not retrieve their contents. Using this object is detailed in Using FormData Objectsbut here are two examples:. You can also bind a FormData object to an element represents a document section containing interactive controls for submitting information.

Using FormData Objects

This creates a FormData object that represents the data contained in the form. You can even get more involved with the process by using the form's elements property to get a list of all of the data elements in the form and manually manage them one at a time. But to send binary data by hand, there's extra work to do.

Unfortunately, some legacy browsers can't access binary data or require complicated workarounds.It is primarily intended for use in sending form data, but can be used independently from forms in order to transmit keyed data. The transmitted data is in the same format that the form's. You can build a FormData object yourself, instantiating it then appending fields to it by calling its append method, like this:.

The field "webmasterfile" is a Blob. A Blob object represents a file-like object of immutable, raw data.

JavaScript Getting The Value Of An Input Field Absolute Beginner

Blobs represent data that isn't necessarily in a JavaScript-native format. The File interface is based on Blobinheriting blob functionality and expanding it to support files on the user's system.

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In order to build a Blob you can invoke the Blob constructor. To construct a FormData object that contains the data from an existing element represents a document section containing interactive controls for submitting information. You can also append additional data to the FormData object between retrieving it from a form and sending it, like this:. This lets you augment the form's data before sending it along, to include additional information that's not necessarily user-editable.

You can also send files using FormData. Simply include an element is used to create interactive controls for web-based forms in order to accept data from the user; a wide variety of types of input data and control widgets are available, depending on the device and user agent. Note : If you pass in a reference to the form, the request method specified in the form will be used over the method specified in the open call. When using the append method it is possible to use the third optional parameter to pass a filename inside the Content-Disposition header that is sent to the server.

When no filename is specified or the parameter isn't supportedthe name "blob" is used. A more recent addition to the platform than the FormData object is the formdata event — this is fired on an element in the DOM; it allows access to and in some cases modification of aspects of the form, as well as access to its component elements. This happens when the form is submitted, but can also be triggered by the invocation of a FormData constructor. This allows a FormData object to be quickly obtained in response to a formdata event firing, rather than needing to put it together yourself.

In our submit event handler we use preventDefault to stop the default form submission, then invoke a FormData constructor to trigger the formdata event:. Note : The formdata event and FormDataEvent object are available in Chrome from version 77 and other equivalent Chromiumsand Firefox 72 first available behind the dom. Get the latest and greatest from MDN delivered straight to your inbox.

Sending forms through JavaScript

Sign in to enjoy the benefits of an MDN account. Note: The fields "userfile" and "webmasterfile" both contain a file. The number assigned to the field "accountnum" is immediately converted into a string by the FormData. Note : FormData will only use input fields that use the name attribute. Last modified: Jan 2,by MDN contributors. Related Topics. Learn the best of web development Get the latest and greatest from MDN delivered straight to your inbox.

The newsletter is offered in English only at the moment. Sign up now. Sign in with Github Sign in with Google.You can also pass it directly to the URLSearchParams constructor if you want to generate query parameters in the way a element represents a document section containing interactive controls for submitting information. An object implementing FormData can directly be used in a for Note : This feature is available in Web Workers.

Get the latest and greatest from MDN delivered straight to your inbox. Sign in to enjoy the benefits of an MDN account. The compatibility table on this page is generated from structured data. Last modified: Mar 18,by MDN contributors. Related Topics.

Learn the best of web development Get the latest and greatest from MDN delivered straight to your inbox. The newsletter is offered in English only at the moment.

Sign up now. Sign in with Github Sign in with Google. Chrome Full support 7. Edge Full support Starting with Firefox 7, the filename blob is sent. IE Full support Opera Full support Safari Full support 5.

Chrome Android Full support Opera Android Full support Safari iOS Full support 5. Samsung Internet Android Full support 1. Firefox Full support 4. Firefox Android Full support 4. Chrome Full support If you want to report an error, or if you want to make a suggestion, do not hesitate to send us an e-mail:. Disable a button Find the name of a button Find the type of a button Find the value of a button Find the text displayed on a button Find the id of the form a button belongs to.

Submit a form Reset a form Find the value of each element in a form Find the accepted character set of a form Find the action attribute of a form Find the value of the enctype attribute in a form Find the number of elements in a form Find the method for sending form data Find the name of a form Find the target of a form.

javascript get form data

Disable and enable a dropdown list Get the id of the form that contains the dropdown list Get the number of options in the dropdown list Turn the dropdown list into a multiline list Select multiple options in a dropdown list Display the selected option in a dropdown list Display all options from a dropdown list Display the index of the selected option in a dropdown list Change the text of the selected option Remove options from a dropdown list.

HOW TO. Your message has been sent to W3Schools. W3Schools is optimized for learning, testing, and training. Examples might be simplified to improve reading and basic understanding. Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content. While using this site, you agree to have read and accepted our terms of usecookie and privacy policy.

Copyright by Refsnes Data. All Rights Reserved. Powered by W3.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Is there a simple, one-line way to get the data of a form as it would be if it was to be submitted in the classic HTML-only way?

Something like this is too simple, since it does not correctly include textareas, selects, radio buttons and checkboxes:. Based on jQuery. We're properly handling a form submit rather than a button press. Some people like to push enter on fields. Some people use alternative input devices such as speech input or other accessibility devices. Handle the form submit and you correctly solve it for everyone.

We're digging into the form data for the actual form that was submitted. If you change your form selector later, you don't have to change the selectors for all the fields. Furthermore, you might have several forms with the same input names. No need to disambiguate with excessive IDs and what not, just track the inputs based on the form that was submitted.

This also enables you to use a single event handler for multiple forms if that is appropriate for your situation. The FormData interface is fairly new, but is well supported by browsers. It's a great way to build that data collection to get the real values of what's in the form. Without it, you're going to have to loop through all the elements such as with form. Totally possible if you need old browser support, but the FormData interface is simpler.

I'm using ES6 here Here is a working JavaScript only implementation which correctly handles checkboxes, radio buttons, and sliders probably other input types as well, but I've only tested these.

If you're looking for a more complete implementation, then take a look at this section of the project I made this for. I'll update this question eventually with the complete solution I came up with, but maybe this will be helpful to someone. First, add an ID to your form unless it is the only form on the page, then you can just use 'form' as the dom query.

Its primarily intended for use in sending form data, but can be used independently from forms in order to transmit keyed data. It takes a form, goes through each input and builds a JSON object you can easily read. I wrote a function that takes care of multiple checkboxes and multiple selects. In those cases it returns an array. As a bonus, it means you don't have to install the entire bundle of jQuery just for one serialize function.

Because this way if you have multiselect list - its values will be overwritten with the last one, since it's transmitted as: "param1" : "value1", "param1" : "value2". This method should do it.