js browser storage webStorage

js browser storage webStorage

The browser implements the local storage mechanism through the Window.sessionStorage and Window.localStorage properties

Related APIs:
The APIs of sessionStorage and localStorage are the same

1. xxxxxStorage.setItem('key','value');
   This method accepts a key and value as parameters, and will add the key-value pair to the storage. If the key name exists, update its corresponding value
2. xxxxxStorage.getItem('key');
   This method accepts a key name as a parameter and returns the value corresponding to the key name
3. xxxxxStorage.removeItem('key');
   This method accepts a key name as a parameter and deletes the key name from the storage
4. xxxxxStorage.clear();
   This method will clear all data in the storage

let p = {
    
    name:'张三',age:18}

function saveData(){
    
    
	localStorage.setItem('msg','hello');
	localStorage.setItem('msg2',666);  //666存储后为字符串
	localStorage.setItem('person',JSON.stringify(p));
}

function readData(){
    
    
	console.log(localStorage.getItem('msg'));
	const result = localStorage.getItem('person');
	console.log(JSON.parse(result));
}

function deleteData(){
    
    
	localStorage.removeItem('msg2');
}

function deleteAllData(){
    
    
	localStorage.clear();
}

• The content stored in sessionStorage will disappear when the browser window is closed
• The content stored in localStorage needs to be manually cleared before it disappears
• xxxxxStorage.getItem(xxx), if the value corresponding to xxx cannot be obtained, then the return value of getItem is null
• The result of JSON.parse(null) is still null