So, we need a new solution, which is the background for the birth of IndexedDB. Generally, IndexedDB is a local database provided by the. The indexeddb is a new HTML5 concept to store the data inside user’s browser. indexeddb is more power than local storage and useful for applications that. IndexedDB is one of the storage capabilities introduced into browsers over the years. Here’s an introduction to IndexedDB, the Database of the.
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As browsers continue growing in functionality, more and more sites are starting to think about storing large amounts of data on the client, which will reduce obtaining data from the server and make data gotten from the local. The Existing browser data storage solutions are not suitable for storing large amounts of data: So, we need a new solution, which is the background for the birth of IndexedDB. Generally, IndexedDB is a local database provided by the browser, and it can be created and gutorial by web scripts.
In the object store, the data is stored in the form of “key-value pairs”. Each data record has its own corresponding primary key, and the primary key is unique and can’t be repeated, otherwise an error will be thrown. It won’t lock the browser when you are operating IndexedDB, and users can still perform other operations, which is in contrast to LocalStorage as it’s synchronous.
Asynchronous design is to prevent the reading and writing of large amounts of data, which will slow down the performance of web pages. IndexedDB supports transactions, which means that as long as one of a series of the steps fails, the entire transaction will be canceled, and the database is rolled back to the state before the transaction occurred.
So there is no case where only a part of the data is rewritten. IndexedDB is subject to homology restriction, and each database corresponds to the domain name that created it. The web page can only access the database which is under its own domain name, but not a cross-domain database. IndexedDB has a much larger storage space than LocalStorage.
Generally it’s more than MB, or even no upper limit.
It abstracts different entities into individual object interfaces. To learning the API is to learn its various object interfaces. A database is a collection of related data. The IndexedDB database has the concept of a version. If you want to modify the database structure indexedd or delete tables, indexes or primary keysyou can only do this by upgrading the database version.
Each database contains several object stores. It is similar to the table indexedrb the relational database. Object store holds data record.
Getting Started with IndexedDB
Each record is similar to the row of a relational database, but with only the primary key and the data body. The primary key is used to establish the default index, which must be different, otherwise an error will be thrown. The primary key can be an attribute in the data record, and it also can be specified as an incremental integer number. In order to speed up the retrieval of data, you can build indexes for different attributes inside the object store.
Getting Started with IndexedDB – CodeProject
It should be done through transaction when you need to read, write or delete data records. IndexedDB database are generally performed by the following process. This section only gives a simple code example for quick start-up. The method takes two arguments, and the first argument inrexeddb represents the name of the database is a string. If the specified database doesn’t exist, a new database will be created.
The second argument thtorial an integer representing the version of the database. If omitted, when opening an existing database, the default is the current tuutorial when creating a new database, the default is 1. Creating a new database is the same as opening a database. If the specified database doesn’t exist, it will create a new one.
The reason why the event is triggered is that the version comes from scratch. Usually, after creating ibdexeddb new database, the first thing is to create a new object store create a new table. A better way to do this is to first determine whether the table exists, and if it doesn’t exist, create a new one then.
The primary key is the index attribute which is built by default. The property of the objects in the next layer iindexeddb also be specified as the primary key. If there is no suitable attribute in the data record as a primary key, then you can make IndexedDB generated a primary key automatically.
Adding data refers to writing data records to an object store. It needs to be done through the transaction. In the above code, you need to create a new transaction in order to write data. The table name and operating mode “Read Only” or “Read and Write” must be specified when creating.
The tutorila of an index is to allow you to search for any field, that is, inedxeddb data record from any field.
If you haven’t built an index, you can only search for the primary key by default take values from the primary key. Overview As browsers continue growing in functionality, more and more sites are starting to think about storing large amounts of data on the client, which will reduce obtaining data from the server and make data tutorkal from the local.
Characteristics of IndexedDB are as follows: IDBDatabase object Object store: IDBTransaction object Operation request: IDBCursor object Primary ttutorial collection: The data body can be any data type and is not limited to objects.
Operation process IndexedDB database are generally performed by the following process. After creating a new object store, the next step is to create a new index.