Question: I set the data to a key called 'todo' in Local Storage.

The structure is like this.

```
key: todo
value : [{"text":"sdf","idx":1,"curTime":"Sun Dec 22 2019","finYN":""}]

```

when a button is clicked, I want to update to "Y" when finYN is empty or "N".

---

If this is my current local storage structure I can use this code but I don't know what to do with the current structure.

```
key: text / value : "sdf"
key: idx / value : 1
key: finYN / value : "Y"

```

> 
> localStorage.setItem("finYN", JSON.stringify ("Y"));
> 
> 
>

Answer: 
If you save the values as a string:

```
localStorage.setItem('todo', JSON.stringify({"text":"sdf","idx":1,"curTime":"Sun Dec 22 2019","finYN":""}));

```

then you can get the value of that localStorage key and turn it back into JSON:

```
var json = JSON.parse(localStorage.getItem('todo'));

```

from here you can easily check the value by accessing `json.finYN` and then changing the JSON and when you are done, you can store it as a string again.
Localstorage values are plain strings, so you cannot manipulate stringified objects. You will have to replace the whole value. 

```
var todos = JSON.parse(localStorage.getItem('todo'));
if(!todos[0]['finYN']){
  todo['finYN'] = 'Y';
  localStorage.setItem('todo',JSON.stringify(todos))
}

```