How to hack a local collection of these JavaScripts. LocalStorage on fingers Localstorage hour of life

Saving data without intermediary in the browser can be impersonal, the main thing is that there is a secure and independent access to the data base. on the Naraziє 4 active methods for this (plus one old one):

1. Local gathering
2. Sesijne skhovische
3. IndexedDB
4. WebSQL (deprecated)

Cookies

Cookie is a classic way to save simple small data in the middle of a document. Sound cookies are forced from the server to the client, which can save them, and then send them back to the server at the next request. Tse mozhe buti vikoristane for such speeches, like cherubing by sessions of oblіkovogo record or vіdstezhennia Koristuvalnytsky information.

Dodatkovo cookies can be twisted and for easy saving data on the client side. Therefore, the stench is also often vikoristovuyutsya for sberіgannya zagalnyh tribute type nalashtuvan koristuvach.

Basic CRUD operations with cookies

// Create document.cookie = "user_name=Ire Aderinokun"; document.cookie = "user_age=25;max-age=31536000;secure"; // Read (All) console.log(document.cookie); // Update document.cookie = "user_age=24;max-age=31536000;secure"; // Delete document.cookie = "user_name=Ire Aderinokun;expires=Thu, 01 Jan 1970 00:00:01 GMT";

Perevagi cookies

• You can twist for communication from the server
• We can assign a term for the cookie to be automatically terminated instead of the one to be cleared manually.

Insufficient cookies

• The stench is getting to the side of the document
• They can save a small amount of money
• The stench can take revenge less than a row.
• Potential problems from security.
• This method is not recommended for collecting data on the client since the Web Storage API (local storage) was introduced.

Support for browsers

Cookies have a basic support for all great browsers.

Local gathering

Local storage is one of a variety of Web Storage APIs, a special API for collecting data from a browser in a key-value format. This API has been created as a solution for cookie problems and is more intuitive and safe way to store simple data in the middle of the browser.

While technically we can save more rows from the local repository, we need to do with the conversion to JSON. In this way, we can save in the local storage of collapsible data in pairs of cookies.

Basic CRUD operations with local storage

// Create const user = (name: "Ire Aderinokun", age: 25) localStorage.setItem("user", JSON.stringify(user)); // Read (Single) console.log(JSON.parse(localStorage.getItem("user"))) // Update const updatedUser = ( name: "Ire Aderinokun", age: 24 ) localStorage.setItem("user", JSON stringify(updatedUser)); // Delete localStorage.removeItem("user");

Advantages of the local treasure

• Promote more simple and intuitive data saving interface.
• More safe for saving data on clients.
• Allows you to save more data (all 3 points - equal to cookies).

Insufficiencies of the local treasure

• Allows you to save more rows

Support for browsers

Sesijne skhovische

This collection is another variation of the Web Storage API. It's exactly the same, like a local collection for a little bit of what data is saved only for the browser tab session. As soon as you log out from the side and close the browser, the data is cleared.

Basic CRUD operations from the session folder

// Create const user = (name: "Ire Aderinokun", age: 25) sessionStorage.setItem("user", JSON.stringify(user)); // Read (Single) console.log(JSON.parse(sessionStorage.getItem("user"))) // Update const updatedUser = ( name: "Ire Aderinokun", age: 24 ) sessionStorage.setItem("user", JSON stringify(updatedUser)); // Delete sessionStorage.removeItem("user");

Perevagi, shortcomings and support in browsers are the same as in a local collection.

IndexedDB

IndexedDB is more cost effective solution for collecting data from the browser, but rather a lower API for collecting a significant amount of structuring data on the client. At its core, it's an object-oriented data base, based on JavaScript, that allows us to easily collect and extract data, indexed behind a key.

WebSQL

WebSQL API for relational base on the client, similar to SQLite. Z 2010 working group W3C has pinned the work on this specification, and this API is no longer part of the HTML specification and is not guilty of hacking.

The Web Storage API ensure that browsers can look over key/value pairs, in the larger world of intuitive fashion there are no cookies.

Web Storage concepts and usage

The two mechanisms behind Web Storage are:

• sessionStorage maintains a separate storage area for each given origin that"s available for duration of the page session (as long as the browser is open, including page reloads and restores)
  • Stores data only for session, meaning that the data is stored until the browser (or tab) is closed.
  • Data is never transferred to the server.
  • Storage limit is larger than a cookie (at most 5MB).
• localStorage does the same thing, but persists even when the browser is closed and reopened.
  • Stores data with no expiration date, and gets cleared only through JavaScript, or clearing the Browser cache / Locally Stored Data.
  • Storage limit is the maximum among the three.

Specifications

Browser compatibility

Window.localStorage

https://github.com/mdn/browser-compat-data and send us a pull request.

Legend

Window.sessionStorage

The compactness of tables on this side is generated from structuring data. If you want to know about your data, click on https://github.com/mdn/browser-compat-data and write.

Update compatibility data on GitHub

Legend

Private Browsing / Incognito modes

Most modern browsers emphasize the possibility of being called "Incognito", "Private Browsing" or some similar fact, which means that this article is like history and cookies. scenarios for how to deal with this incompatibility.

More browsers will be opted for strategy, de Storage APIs to be accessible and super functional, with one great diploma that all data is denied after the browser is closed. For these browsers, the stench is to be filled with different interpretations, as if it were the fault of the vikonan with the obvious entanglement of tribute (such as regular chic). Should it be available to read when in Private mode? There are some browsers, most notably Safari, which will be opted for rozv'azannya, de vantage є explicitly, but є empty and may quota of 0 bytes assigned, effectively making it impossible to write data to it.

Retailers should be made available to these different implementations and be accepted into the public record if the Web sites are reclaimed as a legacy Web Storage APIs. For more information, you can check out the WHATWG blog for specific deals with this topic.

Cookies, as we sorted them in the front row, are also surrounded: in one section there may be less than 4096 characters, and the number of cookies per domain may be approximately 30-50 per browser. That, unfortunately, there is not a lot of information to save there. This is how it happened historically.

To get around this barrier, browsers have an alternative to cookies - it's called a local collection. We can save 5-10 megabytes of information from a local store and send more for three hours.

Work with a local shovish

p align="justify"> To work with a local storage of assignments, the localStorage object will pop up in the browser. Win May 4 Simple Reasoning Methods. Stink Axis:

//Storage value: localStorage.setItem("Key", "Value"); //Retrieving the value: var value = localStorage.getItem("Key"); //Remove value: localStorage.removeItem("Key"); //Clearing all storage: localStorage.clear();

W localStorage you can also practice like a big array:

//Storage value: localStorage["Key"] = "Value"; //Retrieving the value: var value = localStorage["Key"]; //Deleted value: delete localStorage["Key"];

Okrim object localStorageє also object sessionStorage. The work with it works in the same way, the only thing is that all data from the new one is automatically reduced after the browser is closed or the tabs behind the site. Well, localStorage saves data three times a day, until these data are deleted by the script, otherwise the browser's browser clears the local storage for help.

Apply

For each butt, we will write down the name of the koristuvach in the local collection:

LocalStorage.setItem("name", "Ivan");

After a deyaky hour, we take away tse im'ya:

Alert(localStorage.getItem("name"));

Like you bachite - there is nothing coherent here, everything is richly simpler, even the same robot with cookies.

Object conservation

Local collection is not a building to save objects JavaScript arrays I want to often do it manually. Another way is to serialize the data in the JSON format - we will create a row that you can save from localStorage. Then, if we need a distant object back - let's rewrite the row from JSON back to the object - and calmly greet him.

Let's take a look at this process in practice. Serialize the object and save it in the local storage:

// Danish object: var obj = (name: "Ivan", arr:); //Serialize yogo in "("name": "Ivan", "arr" :)): var json = JSON.stringify(obj); //Write to localStorage with obj key: localStorage.setItem("obj", json );

After one hour, we take the object back:

//Retrieve data back from localStorage as JSON: var json = localStorage.getItem("obj"); //Parse them back into a JavaScript object: var obj = JSON.parse(json); console log(obj);

Added capacity

Set the number of records for the storage: alert(localStorage.length).

Name the key by number: alert(localStorage.key(number)).

When vikonannі operation zі shovishem spratsovuє podіyu onstorage. Before you bind a function, then an Event object with the following powers will be available in it:

function func(event) ( var key = event.key; //change data key var oldValue = event.oldValue; //old value var newValue = event.newValue; //new value var storageArea = event.storageArea; //storageArea ; )

Dod. material

Saving the array in the local repository: https://youtu.be/sYUILPMnrIo

What did they give you:

Proceed before the assignment of tasks for the upcoming tasks: task before the lesson.

If everything is wrong, go on to the new topic.

• Lesson #
  playlist on youtube
  Practically buggy ES6

Some videos can jump ahead, because we haven't gone through all of ES6 yet. Just skip this video, marvel later.

Often the first addition to JavaScript is the Todo-list, but the problem of similar programs is that after updating all the items in the list, they appear.

A simple variant of the problem is the victoria local gathering(local storage). Local collection allows you to save data on the machine of the correspondent and you can easily take the list from the next update of the page. In these articles, we will write a small todo-list from the wiki of the local collection.

What is a local treasure?

The local site ("web site") has been part of the HTML5 specification, but has been slammed all over the place. You can save data in two ways:

• local storage: post iyne skhovische, yogo mi will win
• session storage: save the data only for the sessions, as if you close the side, the data will be spent.

The local repository allows you to store data on the computer, and the key-value and data pairs will be available when the browser is closed or the computer is closed.

HTML

To create a todo list, we need:

• Text entry for entering the element in place.
• Button to add an element to the list.
• Button for clearing the list.
• The list itself
  ).
  • І additional div for displaying pardons.

  Such a rank HTML markup look like this:

  Clear All

  Dosit simple structure, yak mi vivably for the help of JavaScript.

  Because we tagged jQuery, it is necessary to add additional connection її.

  JavaScript

  For the cob, we need to press on the add button and check so that the input field was not empty:

  $("#add").click(function() ( var Description = $("#description").val(); if($("#description").val() == "") ( $( "#alert").html(" Warning! You left the empty"); $("#alert").fadeIn().delay(1000).fadeOut(); return false; )

  This code overrides the value of the text input and, as if empty, shows a pardon and turns false, so that part of the code that was left out, did not disappear, and the element did not reach the list.

  // insert record $("#todos").prepend("

  " + Description + "

  // see everything left in the text field $("#form").reset(); var todos = $("#todos").html(); localStorage.setItem("todos", todos); return false;));

  For work with local storage, you need to enter a key and a specific value. Let's name the key 'todos' for our viewpad, and the value will be all the HTML code that goes around the list (the tag

  ). This code is easy to take from help jQuery. I, nareshti, we turn false, to avoid submitting the form and not re-advantage the side.

  Offensive crochet - revise the local repository, if it is the value of the 'todos' key, then grab the list from the local repository:

  If (localStorage.getItem("todos")) ( $("#todos").html(localStorage.getItem("todos")); )

  Because we save prepared HTML from the link, we just paste this code into the list.

  Our todo-list may be ready, no longer implement the function of clearing the list. If you press the button, the entire list will be displayed and the local folder will be cleared:

  $("#clear").click(function() ( window.localStorage.clear(); location.reload(); return false; ));

  Ready! The final code looks like this:

  $(document).ready(function() ( $("#add").click(function() ( var Description = $("#description").val(); if ($("#description")) ).val() == "") ( $("#alert").html(" Warning! You left the to-do empty"); $("#alert").fadeIn().delay(1000).fadeOut(); return false; ) $("#todos").prepend("

  • " + Description + "
  "); $("#form").reset(); var todos = $("#todos").html(); localStorage.setItem("todos", todos); return false; )); .getItem( "todos")) ( $("#todos").html(localStorage.getItem("todos")); ) $("#clear").click(function() ( window.localStorage.clear( );location .reload(); return false; ));

  Support by browsers

  The web site supports all major browsers, like IE8. Be afraid of warto less than IE7 and lower.

  Visnovok

  A local collection in such small programs can become a powerful replacement for the database. Taking care of small amounts of information may be difficult.

  The creation of the “to-do list” program (Amer. to-do list), as a rule, is the first program, as you work with JavaScript, but the problem with all these programs is that if you re-advantage the side, all lists appear.
  Issuing a simple solution - a link to a local collection. The priority of the local collection is those who can save data on the computer of the koristuvach, and if the re-advantage of the party was necessary, all the lists of the date were lost on the site.

  What is a local treasure?

  Local data storage is part of the storage, which itself is part of the HTML5 specification. There are two options for collecting data from the specification:

  • Local storage (Local Storage): collect data without a date of completion of the term di, and the same option, which we will win, so we want our lists to be left on the side of the page.
  • Saving a session (Session Storage): only save data for one session, so if you close the tab and re-open the curve, all data will be spent.

  In simple words, everything that robs a web site does not save key/value wagers locally, and on the page of the cookies, and the data is saved to navigate as soon as you close the browser or turn off the computer.

  If we think about the list of references, then you need:

  • Enter, where can you expand our list
  • Enter button to add a list
  • Button to clear the entire drawer
  • Container of an unordered list, where our list will be placed before the list of elements
  • I, nareshti, we need a DIV container to show information if you try to enter an empty task.

  So, our HTML might look something like this:

  Clear All

  It costs a standard HTML container and with our JavaScript we can fill everything with dynamic content.

  We'll just use jQuery in any application, and we should also include it in the HTML document.

  JavaScript

  If we think about the structure of a simple "to-do list" program, then first, what do we need to add, reverify, what can you enter an empty value, if you press the button "add" or "reverify":

  $("#add").click(function() ( var Description = $("#description").val(); //if the is empty if($("#description").val() ) = = "") ( $("#alert").html(" Warning! You left the empty"); $("#alert").fadeIn().delay(1000).fadeOut(); return false; )

  Everything that we have done, they have misinterpreted the click on the Add button and launched a simple test to verify, as if it were short, to remember the input. If not, then the forward div is merged and delayed for 1000 ms, and then reappears.

  Step forward, as we need to, to insert an element to the list with the values ​​in the input row, and we will change it so that if you add the task, you will always go to the top of the list, and then select the element of the list in the local storage, the axis like this:

  // add the list item $("#todos").prepend("

  " + Description + "

  "); // delete whatever is in the input $("#form").reset(); var todos = $("#todos").html(); localStorage.setItem("todos", todos); false ;));

  If you want to use the standard jQuery and if you get to the local repository on the right, we are to save the key and value. The key is the name, as we ask ourselves, in which case we simply call it "Todos", then we are responsible for what we want to save, and in this case all the HTML that is in the middle of the Todos of the unordered list. As you can see, we all crammed jQuery for help, and we turned the “hibni” so that the form did not give up and our page did not change.

  Our approach is to reconsider, what we have saved at the local collection. If so, then we need to place it on the side, vrakhovy those who gave our key the name “todos”, we need to reverse this background. axis like this:

  // if we will mother a day in the local area, then if(localStorage.getItem("todos")) ( $("#todos").html(localStorage.getItem("todos")); )

  If you are protesting our program and re-advancing the party, please, you are already working. Everything that is left to us to grow, to create a function, as if it will be evidence for the purification of the entire list. We will change all the savings, re-advantage the page, so that our change will get the order, and then turn “false” to save the hash in front of the URL with the next order:

  // clear all the local storage $("#clear").click(function() ( window.localStorage.clear(); location.reload(); return false; ));

  The final code looks like this:
  

  $("#add").click(function() ( var Description = $("#description").val(); if($("#description").val() == "") ( $( "#alert").html(" Warning! You left the to-do empty"); $("#alert").fadeIn().delay(1000).fadeOut(); return false; ) $("#todos").prepend("

  " + Description + "

  "); $("#form").reset(); var todos = $("#todos").html(); localStorage.setItem("todos", todos); return false; )); .getItem( "todos")) ( $("#todos").html(localStorage.getItem("todos")); ) $("#clear").click(function() ( window.localStorage.clear( );location .reload(); return false; ));

  Browser support

  Support for Web Storage is good for HTML5 specifications, it is supported by all major browsers and like IE8.