React / Redux: Actions automatically get called whenever page change - reactjs

Question

I'm making a simple shopping cart app using Redux. Right now every time I change page, actions are automatically get called for three times which is equal to the number of items. If I go to Cart page, removeItems action gets called three times so there's no way I can add items to cart so far. It might be a problem about router, but I can't spot the problem. Could anyone explain me what is the problem?
Home.js
import React from 'react';
import { connect } from 'react-redux';
import { addToCart } from '../actions';
class Home extends React.Component {
handleClick = id => {
this.props.addToCart(id)
}
renderList = () => {
return this.props.cart.slice(0, 3).map(item => {
return (
<div className="card" key={item.id} style={{width: "200px", float: "left", marginRight: "20px"}}>
<div className="card-image">
<img src={item.imageUrl} alt={item.name} />
<span className="card-title">{item.name}</span>
<span to="/"
className="btn-floating halfway-fab waves-effect waves-light red"
onClick={this.handleClick(item.id)}
>
<i className="material-icons">add</i>
</span>
</div>
<div className="card-content">
<p>{item.desc}</p>
<p><b>${item.price}</b></p>
</div>
</div>
)
})
}
render() {
console.log(this.props.cart)
return (
<div className="container">
<h3>Home</h3>
<div className="box">
{this.renderList()}
</div>
</div>
)
}
}
const mapStateToProps = state => {
return { cart: state.cart.items }
}
const mapStateToDispatch = dispatch => {
return {
addToCart: (id) => { dispatch(addToCart(id)) }
}
}
export default connect(mapStateToProps, mapStateToDispatch)(Home);
Cart.js
import React from 'react';
import { connect } from 'react-redux';
import { removeItem } from '../actions';
class Cart extends React.Component {
handleClick = (id) => {
this.props.removeItem(id);
}
renderList = () => {
if (this.props.addedItems.length !== 0) {
return this.props.addedItems.map(item => {
return (
<li className="collection-item avatar" key={item.id}>
<div className="item-img">
<img src={item.imageUrl} alt={item.name} style={{width: "120px"}} />
</div>
<div className="item-desc">
<span className="title">{item.name}</span>
<p>{item.content}</p>
<p><b>${item.price}</b></p>
</div>
<button
className="waves-effect waves-light btn pink remove"
onClick={this.handleClick(item.id)}
>Remove</button>
</li>
)
})
}
else {
return <p>Nothing is in cart.</p>
}
}
render() {
return (
<div className="container">
<div className="cart">
<ul className="collection">
{this.renderList()}
</ul>
</div>
</div>
)
}
}
const mapStateToProps = state => {
return { addedItems: state.cart.addedItems }
}
const mapDispatchToProps = dispatch => {
return {
removeItem: (id) => {dispatch(removeItem(id))}
}
}
export default connect(mapStateToProps, mapDispatchToProps)(Cart);
Header.js
import React from 'react';
import { Link } from 'react-router-dom';
const Header = () => {
return (
<nav className="nav-wrapper">
<div className="container">
<Link to="/" className="brand-logo">Shopping</Link>
<ul className="right">
<li><Link to="/">Shop</Link></li>
<li><Link to="/cart">Cart</Link></li>
<li><Link to="/cart"><i className="material-icons">shopping_cart</i></Link></li>
</ul>
</div>
</nav>
)
}
export default Header;
Reducers
import data from '../data.json';
import { ADD_TO_CART, REMOVE_FROM_CART } from "../actions/types";
const INITIAL_DATA = {
items: data,
addedItems: [],
total: 0
}
const cartReducer = (state = INITIAL_DATA, action) => {
switch(action.type) {
case ADD_TO_CART:
let addedItem = state.items.find(item => item.id === action.id);
let existedItem = state.addedItems.find(item => action.id ===item.id);
if (existedItem) {
addedItem.quantity += 1;
return {
...state,
total: state.total + addedItem.price
}
}
else {
addedItem.quantity = 1;
let newTotal = state.total + addedItem.price;
return {
...state,
addedItems: [...state.addedItems, addedItem],
total: newTotal
}
}
case REMOVE_FROM_CART:
let itemToRemove = state.addedItems.find(item => action.id === item.id);
let newItems = state.addedItems.filter(item => action.id !== item.id);
let newTotal = state.total - itemToRemove.price;
return {
...state,
addedItems: newItems,
total: newTotal
}
default:
return state;
}
}
export default cartReducer;
Actions
import { ADD_TO_CART, REMOVE_FROM_CART } from "./types";
export const addToCart = (id) => {
return {
type: ADD_TO_CART,
id
}
}
export const removeItem = (id) => {
return {
type: REMOVE_FROM_CART,
id
}
}
App.js
import React from 'react';
import { BrowserRouter, Route, Switch } from 'react-router-dom';
import Header from './Header';
import Home from './Home';
import Cart from './Cart';
const App = () => {
return (
<BrowserRouter>
<div className="app">
<Header />
<Switch>
<Route exact path="/" component={Home} />
<Route path="/cart" component={Cart} />
</Switch>
</div>
</BrowserRouter>
)
}
export default App;

Answer 1

Seems like you're actually calling your click handlers whenever you render your components, instead of just passing the handler function, so that's why actions are being triggered multiple times.
For instance, in your Home.js component change the code below from:
<span to="/" className="btn-floating halfway-fab waves-effect waves-light red" onClick={this.handleClick(item.id)} >
to:
<span to="/" className="btn-floating halfway-fab waves-effect waves-light red" onClick={() => { this.handleClick(item.id); }} >
And the same thing on Cart.js, change from:
<button className="waves-effect waves-light btn pink remove" onClick={this.handleClick(item.id)}>Remove</button>
to:
<button className="waves-effect waves-light btn pink remove" onClick={() => {this.handleClick(item.id); }}>Remove</button>