Storing data in html page

Store data with HTML5 local storage

Use the HTML5 local storage to store and read data in the browser. Learn how to store entire objects and how to manipulate data in the storage object. Follow this tutorial to learn all about storing client-side data with JavaScript.

What is HTML5 local storage?

With the HTML5 local storage property, you can store and read data in the browser. It is part of the HTML5 Web Storage API. You can store at least 5MB of data per origin (more on some browsers and devices) and access it from all pages, client-side. The data is accessible across all browser tabs and will still be there after the window has closed and even after closing the browser. It will persist until explicitly deleted.

Local storage is ideal for storing non-critical data client-side. It is easy to use and easy to set-up. You can use it for simple website settings, online tools and even to store progress in web games. Just remember that users can clear the local storage by clearing the browser cache. So important data still needs to be stored somewhere off the client.

Local storage vs cookies

Often, when people think about storing data for a web page, cookies come to mind. There are some big differences between cookies and the local storage.

• Cookies are send to the server with every request, in the HTTP headers. Local storage is not. So it doesn’t effect your website performance .
• Max cookie size is about 4KB , local storage has room for at least 5MB of data. (Depending on the browser and device the page is running on)
• The Storage object offers a nice set of functions to easily manipulate the local storage. Cookies are stored as one long string and you’ll need to implement your own way of dealing with data in a smart and structured way.

Basically, if you need to access data on the client-side, local storage is the way to go. It holds many advantages over using the old fashioned cookie.

Accessibility of data across your website

The local storage object isn’t just available everywhere on your website. It’s specific to the origin of the page and it follows the same-origin policy. Each protocol/domain/port combination has its own local storage object. So the http version of your website has a different local storage object than the https version. The same is true for using different ports or hosts (e.g. www or no-www) on your website. You can’t access the data stored from the other origins.

Here’s a example of whether a page is following the same-origin policy for the fictive URL https://spicyyoghurt.com/tutorial1:

• Same origin — https://spicyyoghurt.com/tutorial2
• Same origin — https://spicyyoghurt.com/javascript-tutorials/tutorial1
• Different protocol — http://spicyyoghurt.com/javascript-tutorials/tutorial2
• Different host — https://www.spicyyoghurt.com/tutorial1
• Different port — https://spicyyoghurt.com:81/javascript-tutorials/tutorial3

Store and read data

Let’s get to the more practical part of this tutorial and actually use the local storage. To manipulate data in the local storage, first get the read-only Storage object from the window.localStorage property. You can access it anywhere in your JavaScript code like this:

 var localStorage = window.localStorage; 

With this reference you can start using the local storage to access and read data.

To store data in the local storage, simply use the setItem() function on the Storage object and pass a key and value . Using a new key will create a new data item, using an existing key will update the previous value.

 localStorage.setItem('myKey', 'myValue'); 

You can retrieve the item again by calling getItem() on the Storage object and passing the key as an argument. The function will return the value matching the key. If the item doesn’t exists, the function will return null .

 let myValue = localStorage.getItem('myKey'); 

Let’s put it to the test and eat a cookie

This little example demonstrates the use of storing data on the client side. You start out with a whole cookie and you can click the eat button to take a bite.

The state of your cookie will be stored in the localStorage . So if you refresh the browser the cookie will still be eaten.

To reset the state of the cookie you can press the bake button. You cookie will be whole again! If you like you can even try to clear your browser cache to do the same. When there is no data on the client the cookie is reverted to its default state (a whole cookie).

Storing other data types, like numbers and booleans

The localStorage can only store strings for each key. Any other data type, like numbers or booleans , need to get converted manually.

Here’s an example of how to store numbers and booleans in the storage:

 let myNumber = 12345; localStorage.setItem('myNumber', myNumber.toString()); let myBoolean = true; localStorage.setItem('myBoolean', myBoolean.toString()); 

When extracting the data you’ll need to convert back from string to the chosen data type. In the example, booleans are stored as false or true. You could also store it as a 0 or 1. It doesn’t matter, as long as you read and write following the same format.

Here’s an example where the data is converted back to it’s original datatype:

 let myNumber = Number(localStorage.getItem('myNumber')); let myBoolean = localStorage.getItem('myBoolean') == 'true'; 

How to store entire JavaScript objects?

Let’s say you don’t just want to store a simple value, but want to save an entire JavaScript object, like the one in the next example. How are you going to fit it in the local storage?

All data items in the local storage are stored as key value pairs, where the values are strings. So if you want to store an entire JavaScript object you’ll have to flatten the object and turn it into a string too. That’s why you need to stringify the object first. You can use JSON.stringify() to convert a JavaScript object into a savable string.

Here’s an example of a simple object getting stored in the local storage:

 let myObject = localStorage.setItem('myObject', JSON.stringify(myObject)); 

You can retrieve the data as you would normally, only this time you’ll have to put the object back together.

The data is retrieved as string and needs to be parsed into an object again. You can use JSON.parse() to do this. Request the value and parse the string to get the JavaScript object back.

In the next example the JavaScript object is read from local storage and stored into a variable after being parsed:

 let myObject = JSON.parse(localStorage.getItem('myObject')); 

Источник

Storing Data in HTML using Javascript: A Step-by-Step Guide

For accessing custom data that needs to be used as an HTML attribute, try using JavaScript. Alternatively, create data-* attributes as explained in the post. To access these attributes, use JS. The solution also suggests adding a new attribute, data-name, to a div with the id of div1 and assigning it a value.

How to store data within a html file using JavaScript

You may want to review this response to determine its effectiveness for your needs.

Typically, a web browser doesn’t function as an HTML editor. This implies that if you make any modifications to an HTML file using a web browser, the changes won’t reflect in the original file.

One possible solution is to create an HTML form that includes a submit button. When the button is clicked, a new HTML file is downloaded. By replacing the old version with the new one, this approach can be effective, depending on the specific situation.

HTML data-* Attribute, The data-* attribute is used to store custom data private to the page or application. The data-* attribute gives us the ability to embed custom data attributes on all HTML elements. The stored (custom) data can then be used in the page’s JavaScript to create a more engaging user experience (without any Ajax calls or …

Storing data in html dynamically (html5)

Try to do it using JavaScript:

SomeClass.someVariable = document.getElementById('divid'); 

In case you intend to retrieve personalized information that needs to be utilized as an attribute in your HTML tags, then employ.

document.getElementById('divid').dataset.XXX; 

This article outlines the usage of attributes that start with «data-«.

This is how you can incorporate create custom attributes into your divs.

Ensure to include the mandatory prefix of data- . Afterward, you can utilize jQuery to retrieve the personalized attribute.

$('#div1').data('text'); => "Hello. This is a custom attribute." 

With this tool, various tasks can be accomplished such as:

if($('#div1').data('text') != "FreddieBobman") < alert("HI!"); >else

The custom attribute will trigger an alert with the message ‘HI!’ as $(‘#div1’).data(‘text’) does not have FreddieBobman, instead it contains the text ‘Hello. This is a custom attribute.’

Utilize the subsequent instructions to produce these characteristics.

The div element with the id of div1 has been assigned a new attribute, specifically data-name with a corresponding value. It is worth noting that attribute values can be modified to suit your preferences.

The data-text in the div now reads «This is cool» instead of «Hello. This is a custom attribute.

By adding the data attributes dynamically to the elements, you can obtain it and retrieve it whenever needed.

 var div = document.createElement('div'); div.setAttribute('data','my_data'); div.innerHTML = "I am a div"; document.body.appendChild(div); 

WORKING DEMO

How, I am building a form in HTML out of a javascript object that I’ve imported from a JSON file. I use a recurisve algorithm to build HTML tables, and respective elements (labels, text boxes, etc.) The fields load with the value of the current node.

How to store HTML form data in local?

One way to utilize localstorage is by implementing it in this manner.

localStorage.setItem('formData', JSON.stringify($('form').serialize())); //comfortable java script way. 

or with cookies you can like this

$.cookie('formData', JSON.stringify($('form').serialize())); //can support old browsers also. 

Check out the accepted answer on storage-vs-cookies for a thorough explanation on which option to choose.

LocalStorage is your best option.

Even if there are thousands of input tags, I’ll need to create code for each one individually.

It’s false. You can accomplish that by employing either a JS loop or a jQuery each.

$("input").each(function()< $(this).val(storage.getItem($(this).attr("id"))); >) .change(function()< storage.setItem($(this).attr("id"), $(this).val()); >); 

Upon page load, content is inserted into each input field according to its unique ID. Subsequently, an event listener is added to all inputs, allowing any changes made to be saved to local storage.

This code is provided for illustrative purposes only and has not been tested. Please note that it may not work immediately, but I trust that you grasp the underlying concept.

How to save user input into a variable in HTML and, var subButton = document.getElementById (‘subButton’); subButton.addEventListener (‘click’, getUserName, false); CodePen demo of this answer. var input = document.getElementById (‘userInput’).value; This will get the value that has been types into the text box, not a DOM object.

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