Zustand for client state in NextJS - Step-by-Step Execution

Concept Flow - Zustand for client state

Create Zustand store

↓

Define state and actions

↓

Use store in component

↓

Component renders with state

↓

User triggers action

↓

Action updates state

↓

Component re-renders with new state

Zustand creates a store with state and actions, components use the store to read state and trigger updates, causing re-render.

Execution Sample

NextJS

import { create } from 'zustand';

const useStore = create(set => ({
  count: 0,
  increment: () => set(state => ({ count: state.count + 1 }))
}));

This code creates a Zustand store with a count state and an increment action to increase count.

Execution Table

Step	Action	State Before	State After	Component Rendered	Output
1	Initialize store	{}	{ count: 0 }	Initial render	count = 0
2	Component reads count	{ count: 0 }	{ count: 0 }	Render with count=0	Displayed 0
3	User clicks increment	{ count: 0 }	{ count: 1 }	Re-render	Displayed 1
4	User clicks increment	{ count: 1 }	{ count: 2 }	Re-render	Displayed 2
5	No further action	{ count: 2 }	{ count: 2 }	No render	Displayed 2

💡 User stops clicking, state remains stable, no re-render occurs.

Variable Tracker

Variable	Start	After 1	After 2	Final
count	0	1	2	2

Key Moments - 3 Insights

Why does the component re-render after calling increment?

Because the increment action updates the state 'count', Zustand triggers a re-render to show the new value, as seen in steps 3 and 4 of the execution_table.

Does the component re-render if the state does not change?

No, if the state stays the same, Zustand does not trigger a re-render. Step 5 shows no render because 'count' did not change.

How does the component get the current state value?

The component calls the store hook (useStore) to read the current 'count' value before rendering, shown in step 2.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of 'count' after step 3?

A 0

B 1

C 2

D Undefined

💡 Hint

Check the 'State After' column in row with Step 3.

At which step does the component first re-render with updated state?

A Step 3

B Step 2

C Step 1

D Step 5

💡 Hint

Look for the first 'Re-render' in the 'Component Rendered' column.

If the increment action did not update the state, what would happen in the execution_table?

A State would reset to 0

B Component would re-render anyway

C State After would be same as State Before and no re-render

D Component would crash

💡 Hint

Refer to step 5 where no state change means no re-render.

Concept Snapshot

Zustand creates a simple store with state and actions.
Use the store hook in components to read state and trigger updates.
Calling an action updates state and causes component re-render.
No state change means no re-render.
Ideal for client state in Next.js apps.

Full Transcript

Zustand is a small library to manage client state in Next.js. You create a store with state variables and actions to update them. Components use the store hook to read state and display it. When an action changes the state, Zustand triggers a re-render so the component shows the new value. If the state does not change, the component does not re-render. This makes state management simple and efficient.