Push JSON Objects to array in localStorage

Question

I have a function in Javascript   var a       function SaveDataToLocalStorage data               var receiveddata   JSON stringify data       a push receiveddata       alert a        localStorage setItem  session   a        the data parameter is a JSON Object    But everytime I click the button it overwrites the data in my localstorage   Does anybody know how to do this

User · Accepted Answer

There are a few steps you need to take to properly store this information in your localStorage. Before we get down to the code however, please note that localStorage (at the current time) cannot hold any data type except for strings. You will need to serialize the array for storage and then parse it back out to make modifications to it.

Step 1:

The First code snippet below should only be run if you are not already storing a serialized array in your localStorage session variable.
To ensure your localStorage is setup properly and storing an array, run the following code snippet first:

var a = [];
a.push(JSON.parse(localStorage.getItem('session')));
localStorage.setItem('session', JSON.stringify(a));

The above code should only be run once and only if you are not already storing an array in your localStorage session variable. If you are already doing this skip to step 2.

Step 2:

Modify your function like so:

function SaveDataToLocalStorage(data)
{
    var a = [];
    // Parse the serialized data back into an aray of objects
    a = JSON.parse(localStorage.getItem('session')) || [];
    // Push the new data (whether it be an object or anything else) onto the array
    a.push(data);
    // Alert the array value
    alert(a);  // Should be something like [Object array]
    // Re-serialize the array back into a string and store it in localStorage
    localStorage.setItem('session', JSON.stringify(a));
}

This should take care of the rest for you. When you parse it out, it will become an array of objects.

Hope this helps.

User · Answer

var arr      a    b    c    arr push  d       insert as last item

User · Answer

One thing I can suggest you is to extend the storage object to handle objects and arrays   LocalStorage can handle only strings so you can achieve that using these methods  Storage prototype setObj   function key  obj        return this setItem key  JSON stringify obj     Storage prototype getObj   function key        return JSON parse this getItem key       Using it every values will be converted to json string on set and parsed on get

User · Answer

Putting a whole array into one localStorage entry is very inefficient  the whole thing needs to be re-encoded every time you add something to the array or change one entry    An alternative is to use http   rhaboo org which stores any JS object  however deeply nested  using a separate localStorage entry for each terminal value  Arrays are restored much more faithfully  including non-numeric properties and various types of sparseness  object prototypes constructors are restored in standard cases and the API is ludicrously simple   var store   Rhaboo persistent  Some name    store write  count   store count   store count 1   1    store write  somethingfancy       one    man    went      2   mow     went     2    mow    a    meadow                   store somethingfancy went 1  mow write 1   lawn      BTW  I wrote it

User · Answer

As of now  you can only store string values in localStorage  You ll need to serialize the array object and then store it in localStorage   For example    localStorage setItem  session   a join          or  localStorage setItem  session   JSON stringify a

[javascript] Push JSON Objects to array in localStorage

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