How to Use KV in Deno Deploy: Simple Guide with Examples

In Deno Deploy, use the built-in kv API to store and retrieve key-value pairs asynchronously. Access it via await kv.get(key) and await kv.set(key, value) inside your request handler to persist data across requests.

Syntax

The kv API in Deno Deploy provides simple methods to store and retrieve data by keys.

• await kv.get(key): Retrieves the value for the given key.
• await kv.set(key, value): Stores the value under the given key.
• await kv.delete(key): Removes the value stored at key.

Keys can be strings or arrays of strings for namespaces. Values can be any JSON-serializable data.

typescript

const value = await kv.get("myKey");
await kv.set("myKey", "myValue");
await kv.delete("myKey");

Example

This example shows a simple Deno Deploy handler that increments a counter stored in KV on each request and returns the current count.

typescript

import { serve } from "https://deno.land/std@0.203.0/http/server.ts";

serve(async (req) => {
  // Get current count or default to 0
  const countEntry = await kv.get(["counter"]);
  const count = (countEntry.value ?? 0) + 1;

  // Store updated count
  await kv.set(["counter"], count);

  return new Response(`Visitor count: ${count}`, {
    headers: { "content-type": "text/plain" },
  });
});

Output

Visitor count: 1
(then increments on each request)

Common Pitfalls

Common mistakes when using kv in Deno Deploy include:

• Not awaiting kv.set or kv.get, causing unexpected behavior.
• Using non-serializable values (like functions or DOM objects) which cause errors.
• Using simple strings as keys without namespaces, which can cause key collisions.
• Assuming immediate consistency; KV operations are eventually consistent in some cases.

typescript

/* Wrong: Missing await causes bugs */
kv.set("key", "value"); // Don't forget await

/* Right: Always await async KV calls */
await kv.set("key", "value");

Quick Reference

Method	Description	Example
get	Retrieve value by key	await kv.get(["user", "123"]);
set	Store value by key	await kv.set(["user", "123"], { name: "Alice" });
delete	Remove value by key	await kv.delete(["user", "123"]);

Key Takeaways

Use await with kv methods to handle asynchronous storage correctly.

Keys can be arrays for better organization and to avoid collisions.

Values must be JSON-serializable to store in KV.

KV storage persists data across requests in Deno Deploy.

Avoid using non-serializable data and always handle possible null returns from kv.get.