I just built a jquery plugin to handle some data storages. When I try to read from storage, the result is the read item data.

But when I add

sessionStorage.setItem('test','some data');

or remove

sessionStorage.removeItem('test');

an item, I always get undefined in the console.log

How can I get rid of the undefined?

What I tried was

var result = sessionStorage.setItem('test','some data');

though this would print it to a var but it doesn't.

My code:

(function ($) {
    
    $.storage = {
    
        add: function(name,value){

            if(typeof value === 'object' )
            {   
                /** convert object to json **/
                value = JSON.stringify(value);
            }
            /** add to storage **/
            sessionStorage.setItem(name,value);
        },
        
        read: function(name){
        
            /** read from storage **/
            var item = sessionStorage.getItem(name);
                try {
                    item = $.parseJSON(item);
                }catch(e){}
            return item;
        },
        
        remove: function(name){
            /** delete from storage **/
            sessionStorage.removeItem(name);
        },
        
        clear: function(){
            /** clear storage **/
            sessionStorage.clear();
        }
        
    }
})(jQuery);

I just built a jquery plugin to handle some data storages. When I try to read from storage, the result is the read item data.

But when I add

sessionStorage.setItem('test','some data');

or remove

sessionStorage.removeItem('test');

an item, I always get undefined in the console.log

How can I get rid of the undefined?

What I tried was

var result = sessionStorage.setItem('test','some data');

though this would print it to a var but it doesn't.

My code:

(function ($) {
    
    $.storage = {
    
        add: function(name,value){

            if(typeof value === 'object' )
            {   
                /** convert object to json **/
                value = JSON.stringify(value);
            }
            /** add to storage **/
            sessionStorage.setItem(name,value);
        },
        
        read: function(name){
        
            /** read from storage **/
            var item = sessionStorage.getItem(name);
                try {
                    item = $.parseJSON(item);
                }catch(e){}
            return item;
        },
        
        remove: function(name){
            /** delete from storage **/
            sessionStorage.removeItem(name);
        },
        
        clear: function(){
            /** clear storage **/
            sessionStorage.clear();
        }
        
    }
})(jQuery);

• javascript
• jquery
• session-storage

• "how can i get rid of the undefined, any ideas ???" — Why do you want to? – Quentin Commented May 7, 2014 at 10:15
• because it seams to be wrong... when i programm, run my application and undefined appears several times... – Dwza Commented May 7, 2014 at 10:16
• @Dwza, I have create a fiddle jsfiddle/satpalsingh/mCNFT using your code. Can you reproduce your problem in fiddle. Also note sessionStorage is supported in IE8+ browser see caniuse./#search=sessionStorage – Satpal Commented May 7, 2014 at 10:58

2 Answers 2

var result = sessionStorage.setItem('test','some data');

does not return anything.

sessionStorage.setItem('test','some data');

assigns value to 'test'therefore the right hand side does not have any value. What you want is

sessionStorage.setItem('test','some data');
var result = sessionStorage.getItem('test'); //<- here the right hand side is 'some data'

setItem and removeItem doesn't return any value. Thus you are getting undefined. Also note removeItem only accept one parameter.

Reference, Here is function sign for above methods

setItem(key:string, data:string):void

This public method stores data via specified key. Please note that if key was already stored, it will overwrite it. Another thing to consider is that if we store a key, and via sessionStorage.key(0) we obtain that key, then we store another key/data and finally we store again the first key, sessionStorage.key(0) will return the second key/data stored, and not the first one.

removeItem(key:string):void

This public method simply removes a key and related data from the storage.