Component only updates after two clicks React

Question

I am building a React app that - among other things - generates a random number when a button is clicked and then filters an array of JSON objects to only the one at the index of that random number (i.e. JSON[random]). Normally the app is supposed to re-render after the array of JSON objects is filtered, but for some reason, on the first time the button is clicked and a random is picked, it requires two clicks to update. From then on it updates as expected, with a new random rendering each time the button is clicked.

I'm not sure if the problem is coming from App.js or somewhere lower down. On the first click, it generates a new random and supposedly saves this to state, but fails to re-render right away. On subsequent clicks, things seem to update based on the previously-generated random, while a new random is put in the queue. I would prefer the this all happens in one go: click, generate random, save to state, update to reflect the new random à la JSON[random].

This might have something to do with the way I have implemented lifecycle methods, as I'm admittedly not sure of all the nuances of each and have just tried to use whichever ones seemed to do what I wanted. If you have any suggestions there, please let me know...

Thanks!

Here are the relevant files:

App.js - where the random is generated and stored when a new click is registered in Header.state.randomClicks

class App extends Component {
  constructor(props){
    super(props)
    this.state = {headerLink: "", searchValue: "", random: 0, randomClicks: 0}

    this.generateRandom = this.generateRandom.bind(this);
  }

  getLinkFromHeader = (link) => {
    if (this.state.headerLink !== link) {
      this.setState({
        headerLink: link,
      })
    }
  }

  getSearchValueFromHeader = (string) => {
    this.setState({
      searchValue: string,
    });
  }

  getRandomMax = (max) => {
    this.setState({
      randomMax: max,
    })
  }

  getRandomClicks = (value) => {
    this.setState({
      randomClicks: value,
    })
  }

  generateRandom(number) {
    let random = Math.floor(Math.random() * number) + 1;
    console.log("generateRandom = ", random)
    return random
  }

  shouldComponentUpdate(nextProps, nextState) {
    return this.state.randomClicks !== nextState.randomClicks;
  }

  componentWillUpdate() {}

  componentDidUpdate(prevState) {
    let randomClicks = this.state.randomClicks;
    console.log("this.state.randomClicks: ", this.state.randomClicks)
    // console.log("prevState: ", prevState)
    // console.log("prevState.randomClicks = ", prevState.randomClicks)
    // ^^ is this a bug ? ^^
    let random = this.generateRandom(this.state.randomMax);
    if (this.state.random !== random) {
      this.setState({random: random})
    }
  }

  render() {
    return (
      
        
          
          
        
      
    );
  }
}

export default App

Header.js* - where the randomClick count is incremented each time RandomButton is clicked

class Header extends Component {
  constructor(props){
    super(props);
    this.state = { selectorLink: "", searchValue: "", randomClicks: 0 }

    this.randomClick = this.randomClick.bind(this);
  }


  getLinkFromSelector = (link) => {
    this.setState({
      selectorLink: link,
    })
  }

  getSearchValue = (string) => {
    this.setState({
      searchValue: string,
    })
  }

  shouldComponentUpdate(nextProps, nextState) {
    console.log("this.state !== nextState: ", this.state !== nextState)
    return this.state !== nextState;
  }

  componentDidUpdate(previousState){
    if(this.state.selectorLink !== previousState.selectorLink) {
      this.props.getLinkFromHeader(this.state.selectorLink);
    }
    this.props.getSearchValueFromHeader(this.state.searchValue);
    this.props.getRandomClicks(this.state.randomClicks);
    console.log("Header Did Update")
  }

  randomClick(){
    this.props.randomClick;
    this.setState({
      randomClicks: this.state.randomClicks += 1,
    });
  }

  render(){
    return(
      

        
          
            Pokédex Viewer App
          
        

        

        

        
        

      
    )
  }
}

export default Header

TilesContainer.js - where the random number from App is sent and the tiles list is filtered/re-rendered

class TilesContainer extends Component {

  constructor(props){
    super(props);
    this.state = {
        pokemon: [],
        filteredPokemon: [],
        randomMax: 0,
        showDetails: false,
      };
    this.getPokemon = this.getPokemon.bind(this);
    this.tiles = this.tiles.bind(this);
    this.getPokemon(this.props.link);
  }

  getPokemon(pokedexLink) {
    let link = "";
    (pokedexLink === "")
      ? link = "https://pokeapi.co/api/v2/pokedex/national/"
      : link = this.props.link;
      fetch(link)
      .then(response => response.json())
      .then(myJson => {
        let list = myJson['pokemon_entries'];
        this.setState({
          pokemon: list,
          randomMax: list.length,
        })
        this.props.getRandomMax; // send randomMax to App
      })
  }

  filterPokemon(string) {
    if (string !== "") {
        console.log("string: ", string)
        string = string.toString().toLowerCase()
        let filteredPokemon =  this.state.pokemon.filter(pokemon => {
        const name = pokemon.pokemon_species.name;
        const nameStr = name.slice(0,string.length);
        const number = pokemon.entry_number;
        const numberStr = number.toString().slice(0, string.length);
        return (this.state.random !== 0) ? number.toString() === string : nameStr === string || numberStr === string;
      })
      if (this.props.randomClicks !== 0) { // i.e. using a random
        this.setState({
          filteredPokemon: filteredPokemon,
        })
      } else {
        this.setState({
          filteredPokemon: filteredPokemon,
          randomMax: filteredPokemon.length,
        })
      }
    } else {
      this.setState({
        filteredPokemon: [],
        randomMax: this.state.pokemon.length,
      })
    }
  }


  componentDidUpdate(prevProps, prevState) {
    if (this.props.link !== prevProps.link) {
      this.getPokemon(this.props.link)
    }
    if (this.props.searchValue !== prevProps.searchValue) {
      this.filterPokemon(this.props.searchValue)
    }
    if (this.state.randomMax !== prevState.randomMax){
      this.props.getRandomMax(this.state.randomMax);
    }
    if (this.props.random !== prevProps.random) {
      console.log("TilesContainer random: ", this.props.random)
      this.filterPokemon(this.props.random)
    }
  }

  tiles() {
    console.log("tiles() filteredPokemon: ", this.state.filteredPokemon)
    console.log("tiles() searchValue: ", this.props.searchValue)
    console.log("tiles() random: ", this.props.random)
    if (this.state.pokemon.length > 0) {
      if (this.state.filteredPokemon.length == 0 && this.props.searchValue === ""){
        return (
            this.state.pokemon.map(pokemon => (
            
          ))
        )
      } else if (this.state.filteredPokemon.length > 0){
        return (
            this.state.filteredPokemon.map(pokemon => (
            
          ))
        )
      }

    }
  }

  render(){
    return (
      
             {this.tiles()}
      
    )
  }
}

export default TilesContainer

Component only updates after two clicks React

Answers (1)

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