Localstorage analysis: What type of database technology is it?

Understand localstorage: What kind of database technology is it?

In Web development, data storage and processing have always been an important issue. With the continuous development of computer technology, various database technologies have also appeared one after another. Among them, localstorage is a widely used database technology. It is a local storage solution provided by HTML5 that can store and read data in the browser. This article will introduce the characteristics and usage of localstorage, and give specific code examples.

1. Features of localstorage

1. Permanent storage: The data saved in localstorage will not be lost due to page refresh or closing, unless manually deleted or cleared browser cache. This makes localstorage ideal for storing data that needs to be preserved for a long time, such as users' personal settings and preferences.
2. 5MB size limit: HTML5 stipulates that the maximum capacity of localstorage under each domain name is 5MB. Although the capacity is limited, it is enough to save a small amount of text, numbers, small pictures and other data.
3. Key-value pair storage: localstorage stores data in the form of key-value pairs, each key-value pair is a string. The stored values ​​can be strings, numbers, Boolean values, objects, etc.
4. Mainly used for front-end storage: localstorage is mainly used for front-end storage, storing and accessing data are performed in the browser. This makes localstorage faster and simpler than traditional backend databases.

2. How to use localstorage

1. Storing data: You can use the setItem() method of the localstorage object to store data. The setItem() method accepts two parameters, the first parameter is the key name, and the second parameter is the value.

Sample code:

localStorage.setItem("username", "张三");
localStorage.setItem("age", 18);
localStorage.setItem("isVIP", true);

2. Reading data: You can use the getItem() method of the localstorage object to read data. The getItem() method accepts one parameter, which is the key name.

Sample code:

var username = localStorage.getItem("username");
var age = localStorage.getItem("age");
var isVIP = localStorage.getItem("isVIP");
console.log(username);  // 输出：张三
console.log(age);  // 输出：18
console.log(isVIP);  // 输出：true

3. Modify data: If you want to modify the stored data, just use the setItem() method to reset the value corresponding to the key name. .

Sample code:

localStorage.setItem("age", 19);
var age = localStorage.getItem("age");
console.log(age);  // 输出：19

4. Delete data: You can use the removeItem() method of the localstorage object to delete stored data. The removeItem() method accepts one parameter, which is the key name.

Sample code:

localStorage.removeItem("isVIP");
var isVIP = localStorage.getItem("isVIP");
console.log(isVIP);  // 输出：null

3. Compatibility of localstorage
As part of HTML5, most modern browsers support localstorage. However, in order to ensure compatibility, you can use the following code to determine whether the browser supports localstorage:

if (typeof(Storage) !== "undefined") {
    // 浏览器支持localstorage
} else {
    // 浏览器不支持localstorage
}

On some older versions of browsers, localstorage may not be supported. At this time, other storage methods such as cookies can be used instead.

Summary:
This article introduces the characteristics and usage of localstorage. As a local storage technology, localstorage has the characteristics of permanent storage, 5MB size limit, key-value storage, etc., and is suitable for front-end storage of smaller amounts of data. Data can be stored and read easily through setItem(), getItem(), removeItem() and other methods. I hope this article will help everyone understand localstorage and provide corresponding code examples.

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