How to update a specific value from the array in local storage?-CodePudding

There is an array of strings in the local storage. I want to find a specific value from that array, and update only that specific value without changing the rest of the array.

function saveLocalChecked(task) {
    let tasks = JSON.parse(localStorage.getItem('tasks'));
    const taskIndex = task.children[1].innerText;

    for(let i = 0; i < tasks.length; i  ) {
        if(tasks[i] === taskIndex) {
            localStorage.setItem('tasks', JSON.stringify(tasks[i]   '*'));
        }
    }
}

So, in this function, I create the tasks array by pulling the items from the local storage. In the for loop, I loop over the tasks array to find a specific element. And now, I want to update that element by concatenating the asterisk sign. But after checking my local storage, there is only that updated element, and the rest of the array just disappeared.

How to fix this?

CodePudding user response：

That is because you are replacing the entire storage for that specific array with the one single element you apply the change to. Change the item you want within your if condition and send the entire array, with the updated element, back to storage

function saveLocalChecked(task) {
    let tasks = JSON.parse(localStorage.getItem('tasks'));
    const taskIndex = task.children[1].innerText;

    for(let i = 0; i < tasks.length; i  ) {
        if(tasks[i] === taskIndex) {
            tasks[i] = tasks[i]   '*'
            localStorage.setItem('tasks', JSON.stringify(tasks));
        }
    }
}

CodePudding user response：

You can always retrieve data from localstorage, modify the data and store it again. In your case, you can directly modify the array tasks before storing the modified array in local storage again.

function saveLocalChecked(task) {
    let tasks = JSON.parse(localStorage.getItem('tasks'));
    const taskIndex = task.children[1].innerText;

    //Modify elements
    for(let i = 0; i < tasks.length; i  ) {
        if(tasks[i] === taskIndex) {
            tasks[i] ='*';
        }
    }
   
    //Store modified array in localstorage
    localStorage.setItem('tasks', JSON.stringify(tasks));
}