Filter with setState not working. React

Question

I have that code, I'm not getting filter. I want to filter all that have the letter “a” but it looks like the SetState is not working. I can't find the error, someone could help me?

it looks like it's the setstate that not working. And where is "a" it will be a value of input.

I go after trying to make a search function that renders the name of the people that is matched in a search text input.

 class Pagination extends React.Component { constructor() { super(); this.state = { elementsPerPage:3, currentPage:0, peoples:[ {id:0, name:"aaa"}, {id:1, name:"bb"}, {id:2, name:"aa"}, {id:3, name:"cc"}, {id:4, name:"dada"}, {id:5, name:"Daddi"}, {id:6, name:"Dwe"}, {id:7, name:"ta"}, {id:8, name:"lala"}, {id:9, name:"lele"}, {id:10, name:"f"}, {id:11, name:"a"}], input: "", filtered: [], }; this.nextPage = this.nextPage.bind(this); this.previousPage = this.previousPage.bind(this); this.filterNames = this.filterNames.bind(this); this.getValueInput = this.getValueInput.bind(this); } getValueInput (value) { this.setState({ input: value.target.value }); } filterNames (){ const {peoples, filtered} = this.state; console.log(this.state.filtered) this.filtered = this.state.filtered.filter(item => item.includes('a')) this.setState({filtered: this.filtered }) } elementsOnScreen () { const {elementsPerPage, currentPage, peoples} = this.state; const namesInFiltered = this.state.filtered = peoples.map(item => item.name) return namesInFiltered.map((nome) => <li>{nome}</li>) .slice(currentPage*elementsPerPage, currentPage*elementsPerPage + elementsPerPage) } nextPage () { const {elementsPerPage, currentPage, peoples} = this.state; if((currentPage+1) * elementsPerPage < peoples.length){ this.setState({ currentPage: this.state.currentPage + 1 }); console.log(this.state.currentPage) } } previousPage () { const { currentPage } = this.state; if(currentPage - 1 >= 0){ this.setState({ currentPage: this.state.currentPage - 1 }); } } render() { return ( <div> <input type="text" onChange={ this.getValueInput }></input> <button className='search' onClick={this.filterNames}> Search </button> <button onClick={this.previousPage}> Previous </button> <button onClick={this.nextPage}> Next </button> <ul>Names: {this.elementsOnScreen()}</ul> <h3>Current Page: {this.state.currentPage}</h3> </div> ); } } ReactDOM.render( <Pagination/>, document.getElementById('root') ) 

 <div id="root"></div> 

Answer 1

Lets sort out a few things. people is actually not a state, but rather a property. Also you create some chaos in your state, the elemelts should actually not be part of the state at all

 function keyIncludes(key, value) {
   return el => el[key].includes(value);
 }

 function onPage(page, perPage) {
   return (_, i) => i >= (page - 1) * perPage && i < page * perPage;
 }

 class Pagination extends React.Component {
   constructor(props) {
     super(props);
     this.state = {
       elementsPerPage:3,
       currentPage:0,
       input: ""
     };
   }

  elementsOnScreen() {
    return this.props.people
       .filter(keyIncludes("name", this.state.input))
       .filter(onPage(this.state.currentPage, this.state.elementsPerPage));
  }

   render() {
     return (
        <div>
          <input type="text" onChange = {() => this.handleChange()} />
         <button onClick={() => this.previousPage()}> Previous </button>
        <button onClick={this.nextPage}> Next </button>
        <ul>Names: {this.elementsOnScreen()}</ul>
        <h3>Current Page: {this.state.currentPage}</h3>
       </div>
    );
  }

  /*...*/
 }