14.10 Dispatching Actions From Within Component

Counter.js

Counter.js

import React, { Component } from "react";
import { connect } from "react-redux";
import CounterControl from "../../components/CounterControl/CounterControl";
import CounterOutput from "../../components/CounterOutput/CounterOutput";

class Counter extends Component {
  state = {
    counter: 0,
  };

  counterChangedHandler = (action, value) => {
    switch (action) {
      case "inc":
        this.setState((prevState) => {
          return { counter: prevState.counter + 1 };
        });
        break;
      case "dec":
        this.setState((prevState) => {
          return { counter: prevState.counter - 1 };
        });
        break;
      case "add":
        this.setState((prevState) => {
          return { counter: prevState.counter + value };
        });
        break;
      case "sub":
        this.setState((prevState) => {
          return { counter: prevState.counter - value };
        });
        break;
    }
  };

  render() {
    return (
      <div>
        <CounterOutput value={this.props.ctr} />
        <CounterControl
          label="Increment"
          clicked={this.props.onIncrementCounter}
        />
        <CounterControl
          label="Decrement"
          clicked={() => this.counterChangedHandler("dec")}
        />
        <CounterControl
          label="Add 5"
          clicked={() => this.counterChangedHandler("add", 5)}
        />
        <CounterControl
          label="Subtract 5"
          clicked={() => this.counterChangedHandler("sub", 5)}
        />
      </div>
    );
  }
}

const mapStateToProps = (state) => {
  return {
    ctr: state.counter,
  };
};

const mapDispatchToProps = (dispatch) => {
  return {
    onIncrementCounter: () => dispatch({ type: "INCREMENT" }),
  };
};
export default connect(mapStateToProps, mapDispatchToProps)(Counter);

reducer.js

reducer.js

const initialState = {
  counter: 0,
};

const reducer = (state = initialState, action) => {
  if (action.type === "INCREMENT") {
    return {
      counter: state.counter + 1,
    };
  }
  return state;
};

export default reducer;