How to store value from local storage in an array, JavaScript?

Question

I have been trying to code in javascript where I want input given to be displayed on screen. I want to store the data from input in LocalStorage. I tried to take the value and using localStorage.setItem and localStorage.getItem I stored in local storage too. But as I want to display all the records I have inserted every time submit button has been clicked, I want to store current and previous records too. I tried to push into an array but it had only current records and not previously stored values. I don't want jquery. I just want simple javascript code. thank you.

   eg-
    var data=[];
    function myFunction(data)
    { 
         var name= document.getElementById("nm").value;
         localStorage.name= name;
         for(var i=0;i<localStorage.length;i++)
         {
             var key = localStorage.key(i);
             var value = localStorage.getItem(key);
             data.push( value);
         }
     }

Please show how you currently store the data also. Would be simplest to store json representation of array and then parse the when getting it out of storage. A convenient little library script is Store.js — charlietfl
– charlietfl, Commented May 29, 2016 at 15:40

Vivek Pradhan · Accepted Answer · 2016-05-29 16:39:56Z

2

Yep, as mentioned in the comments it is best to just store the String representation of your array and store it as a value in localstorage. Web localstorage lets you store simple key value pairs which can be integers or strings (mostly strings) official docs

You could do something like this:

 var name= document.getElementById("nm").value;
 var data;
 if (localStorage.getItem("name") === null)
   //First value to be stored
   data = [];
 else
   //There is some value already in the array
   data = JSON.parse(localStorage.getItem("name"));

 //Push name to data array in any case
 data.push(name);
 //Update localStorage
 localStorage.setItem("name",JSON.stringify(data));

I hope this gets you started in the right direction.

edited May 29, 2016 at 16:39

answered May 29, 2016 at 15:48

Vivek Pradhan

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4 Comments

RomanPerekhrest Over a year ago

localStorage.setItem("name") = JSON.stringify(data) - this is wrong usage of localStorage.setItem(key, value) method

Vivek Pradhan Over a year ago

@RomanPerekhrest, thanks a ton for pointed it out! Noted and updated :)

Sarah Over a year ago

Thank u for the ans, but its giving data.push is nt a function error. why? eventhough data is an array

Vivek Pradhan Over a year ago

@Sarah, sorry for the late reply. Try doing typeof(data) where you are getting the error. It should ideally be an array. We can force it during declaration so where I do var data;, try var data=[]; and see if it solves your problem.

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