adding objects to array in localStorage

Question

Ok, I\'ve tried to follow examples here, I know there might be a few different ways of adding objects to an array in localstorage and not overwriting it but I\'m failing to

Answer 1

adding objects to array in localStorage (Ionic):

var existingEntries = JSON.parse(localStorage.getItem("allEntries"));
if(existingEntries == null) existingEntries = [];
var testObject ={username:this.username, 
mobile:this.mobile,
email:this.email,
type:this.type,
password:this.password};

localStorage.setItem('testObject', JSON.stringify(testObject));
existingEntries.push(testObject);
localStorage.setItem("allEntries", JSON.stringify(existingEntries));

Answer 2

const object = {
name: 'ayyan',
age: 29,
number: 03070084689,
};
const arr = JSON.parse(localstorage.getItem('key_name')) || [];
arr.push(object);
localstorage.setitem(json.strigify('key_name', arr);

Answer 3

Maybe you just need to fetch the entries before pushing the new one:

var allEntries = JSON.parse(localStorage.getItem("allEntries")) || [];
allEntries.push(entry); 
//etc...

Answer 4

When you use setItem it overwrites the item which was there before it. You need to use getItem to retrieve the old list, append to it, then save it back to localStorage:

function addEntry() {
    // Parse any JSON previously stored in allEntries
    var existingEntries = JSON.parse(localStorage.getItem("allEntries"));
    if(existingEntries == null) existingEntries = [];
    var entryTitle = document.getElementById("entryTitle").value;
    var entryText = document.getElementById("entryText").value;
    var entry = {
        "title": entryTitle,
        "text": entryText
    };
    localStorage.setItem("entry", JSON.stringify(entry));
    // Save allEntries back to local storage
    existingEntries.push(entry);
    localStorage.setItem("allEntries", JSON.stringify(existingEntries));
};

Here is a fiddle which demonstrates the above.

Answer 5

HTML5 localStorage lets you store key/value pairs of data. Both key and value needs to be a string. To store arrays as a key or value you need to encode the array into a JSON string. And while retrieving you need to decode it back to an array.

const object = {
name: 'ayyan',
age: 29,
number: 03070084689,
};
const arr = JSON.parse(localstorage.getItem('key_name')) || [];
const data = [arr, ...[object]];
localstorage.setitem(json.strigify('key', data);