Blazor LocalStorageService

ILocalStorageService.cs

public interface ILocalStorageService
{
    Task SetAsync<T>(string key, T item)  where T: class;

    Task SetStringAsync(string key, string value);

    Task<T> GetAsync<T>(string key)  where T: class;

    Task<string> GetStringAsync(string key);

    Task RemoveAsync(string key);
}

public class LocalStorageService : ILocalStorageService
{
    private readonly IJSRuntime _jsRuntime;

    public LocalStorageService(IJSRuntime jsRuntime)
    {
        _jsRuntime = jsRuntime;
    }

    public async Task SetAsync<T>(string key, T item)  where T: class
    {
        var data = JsonSerializer.Serialize(item);
        await _jsRuntime.InvokeVoidAsync("set", key, data);
    }

    public Task SetStringAsync(string key, string value)
    {
        _jsRuntime.InvokeAsync<string>("set", key, value);
        return Task.CompletedTask;
    }

    public async Task<T> GetAsync<T>(string key)  where T: class
    {
        var data = await _jsRuntime.InvokeAsync<string>("get", key);
        if (string.IsNullOrEmpty(data))
        {
            return null!;
        }
        return JsonSerializer.Deserialize<T>(data)!;
    }

    public async Task<string> GetStringAsync(string key)
    {
        return await _jsRuntime.InvokeAsync<string>("get", key);
    }

    public Task RemoveAsync(string key)
    {
        _jsRuntime.InvokeAsync<string>("remove", key);
        return Task.CompletedTask;
    }
}

js-interopt.js

function message(e) { alert(e); }
function set(key, value) { localStorage.setItem(key, value); }
function get(key) { return localStorage.getItem(key); }
function remove(key) { return localStorage.removeItem(key); }