I have a gallery that show images, and i have a search textbox Im Trying to use Timeout on Input event to prevent the api call on every letter im typing : I try to handle the event with doSearch function onChange: but now I cant write anything on the textbox and it cause many errors Attached to this session the app and gallery ponents

Thanks in advance

class App extends React.Component {
  static propTypes = {
  };

  constructor() {
    super();
    this.timeout =  0;
    this.state = {
      tag: 'art'
    };
  }


  doSearch(event){
    var searchText = event.target.value; // this is the search text
    if(this.timeout) clearTimeout(this.timeout);
    this.timeout = setTimeout(function(){this.setState({tag: event.target.value})} , 500);
  }

  render() {
    return (
      <div className="app-root">
        <div className="app-header">
          <h2>Gallery</h2>
          <input className="input" onChange={event => this.doSearch(event)} value={this.state.tag}/>
        </div>
        <Gallery tag={this.state.tag}/>
      </div>
    );
  }
}

export default App;

This is the Gallery class:

import React from 'react';
import PropTypes from 'prop-types';
import axios from 'axios';
import Image from '../Image';
import './Gallery.scss';

class Gallery extends React.Component {
  static propTypes = {
    tag: PropTypes.string
  };

  constructor(props) {
    super(props);
    this.state = {
      images: [],
      galleryWidth: this.getGalleryWidth()

    };
  }

  getGalleryWidth(){
    try {
      return document.body.clientWidth;
    } catch (e) {
      return 1000;
    }
  }
  getImages(tag) {
    const getImagesUrl = `services/rest/?method=flickr.photos.search&api_key=522c1f9009ca3609bcbaf08545f067ad&tags=${tag}&tag_mode=any&per_page=100&format=json&safe_search=1&nojsoncallback=1`;
    const baseUrl = '/';
    axios({
      url: getImagesUrl,
      baseURL: baseUrl,
      method: 'GET'
    })
      .then(res => res.data)
      .then(res => {
        if (
          res &&
          res.photos &&
          res.photos.photo &&
          res.photos.photo.length > 0
        ) {
          this.setState({images: res.photos.photo});
        }
      });
  }

  ponentDidMount() {
    this.getImages(this.props.tag);
    this.setState({
      galleryWidth: document.body.clientWidth
    });
  }

  ponentWillReceiveProps(props) {
    this.getImages(props.tag);
  }

  render() {
    return (
      <div className="gallery-root">
        {this.state.images.map((dto , i) => {
          return <Image key={'image-' + dto.id+ i.toString()} dto={dto} galleryWidth={this.state.galleryWidth}/>;
        })}
      </div>
    );
  }
}

I have a gallery that show images, and i have a search textbox Im Trying to use Timeout on Input event to prevent the api call on every letter im typing : I try to handle the event with doSearch function onChange: but now I cant write anything on the textbox and it cause many errors Attached to this session the app and gallery ponents

Thanks in advance

class App extends React.Component {
  static propTypes = {
  };

  constructor() {
    super();
    this.timeout =  0;
    this.state = {
      tag: 'art'
    };
  }


  doSearch(event){
    var searchText = event.target.value; // this is the search text
    if(this.timeout) clearTimeout(this.timeout);
    this.timeout = setTimeout(function(){this.setState({tag: event.target.value})} , 500);
  }

  render() {
    return (
      <div className="app-root">
        <div className="app-header">
          <h2>Gallery</h2>
          <input className="input" onChange={event => this.doSearch(event)} value={this.state.tag}/>
        </div>
        <Gallery tag={this.state.tag}/>
      </div>
    );
  }
}

export default App;

This is the Gallery class:

import React from 'react';
import PropTypes from 'prop-types';
import axios from 'axios';
import Image from '../Image';
import './Gallery.scss';

class Gallery extends React.Component {
  static propTypes = {
    tag: PropTypes.string
  };

  constructor(props) {
    super(props);
    this.state = {
      images: [],
      galleryWidth: this.getGalleryWidth()

    };
  }

  getGalleryWidth(){
    try {
      return document.body.clientWidth;
    } catch (e) {
      return 1000;
    }
  }
  getImages(tag) {
    const getImagesUrl = `services/rest/?method=flickr.photos.search&api_key=522c1f9009ca3609bcbaf08545f067ad&tags=${tag}&tag_mode=any&per_page=100&format=json&safe_search=1&nojsoncallback=1`;
    const baseUrl = 'https://api.flickr./';
    axios({
      url: getImagesUrl,
      baseURL: baseUrl,
      method: 'GET'
    })
      .then(res => res.data)
      .then(res => {
        if (
          res &&
          res.photos &&
          res.photos.photo &&
          res.photos.photo.length > 0
        ) {
          this.setState({images: res.photos.photo});
        }
      });
  }

  ponentDidMount() {
    this.getImages(this.props.tag);
    this.setState({
      galleryWidth: document.body.clientWidth
    });
  }

  ponentWillReceiveProps(props) {
    this.getImages(props.tag);
  }

  render() {
    return (
      <div className="gallery-root">
        {this.state.images.map((dto , i) => {
          return <Image key={'image-' + dto.id+ i.toString()} dto={dto} galleryWidth={this.state.galleryWidth}/>;
        })}
      </div>
    );
  }
}

• javascript
• reactjs
• settimeout
• inputbox

• Just replace the function you're passing to setTimeout with an arrow function (setTimeout(() => this.setState(...))) to preserve lexical scope. – haim770 Commented Aug 15, 2018 at 9:09

3 Answers 3

First of all why do you need to use setTimeout to set value that is entered by user. I don't see any use using setTimeout in doSearch function.

The reason your doSearch function won't work because you are not binding it.

You can directly set value to tag using setState in doSearch function in following ways.

ES5 way

constructor(props){
    super(props);
    this.doSearch = this.doSearch.bind(this);
}

doSearch(event){
    this.setState({
       tag: event.target.value
    });
}

ES6 way

doSearch = (event) => {
    this.setState({
       tag: event.target.value
    });
}

Doing setState inside setTimeout in doSearch function won't work because input tag has value assigned.

ES5 way

constructor(props){
    super(props);
    this.doSearch = this.doSearch.bind(this);
}

doSearch(event){
     if(this.timeout) clearTimeout(this.timeout);
     this.timeout = setTimeout(function(){
       this.setState({
          tag: event.target.value
       }) 
     }.bind(this),500);
}

setTimeout in ES6 way

doSearch = (event) => {
     if(this.timeout) clearTimeout(this.timeout);
     this.timeout = setTimeout(() => {
       this.setState({
          tag: event.target.value
       }) 
     },500);
}

Gallery ponent:

Check current props changes with previous change in ponentWillRecieveProps to avoid extra renderings.

Try with below updated code

import React from 'react';
import PropTypes from 'prop-types';
import axios from 'axios';
import Image from '../Image';
import './Gallery.scss';

class Gallery extends React.Component {
  static propTypes = {
    tag: PropTypes.string
  };

  constructor(props) {
    super(props);
    this.state = {
      images: [],
      galleryWidth: this.getGalleryWidth()

    };
  }

  getGalleryWidth(){
    try {
      return document.body.clientWidth;
    } catch (e) {
      return 1000;
    }
  }
  getImages(tag) {
    const getImagesUrl = `services/rest/?method=flickr.photos.search&api_key=522c1f9009ca3609bcbaf08545f067ad&tags=${tag}&tag_mode=any&per_page=100&format=json&safe_search=1&nojsoncallback=1`;
    const baseUrl = 'https://api.flickr./';
    axios({
      url: getImagesUrl,
      baseURL: baseUrl,
      method: 'GET'
    })
      .then(res => res.data)
      .then(res => {
        if (
          res &&
          res.photos &&
          res.photos.photo &&
          res.photos.photo.length > 0
        ) {
          this.setState({images: res.photos.photo});
        }
      });
  }

  ponentDidMount() {
    this.getImages(this.props.tag);
    this.setState({
      galleryWidth: document.body.clientWidth
    });
  }

  ponentWillReceiveProps(nextProps) {
     if(nextProps.tag != this.props.tag){
        this.getImages(props.tag);
     }
  }

  shouldComponentUpdate(nextProps, nextState) {
      if(this.props.tag == nextProps.tag){
          return false;
      }else{
          return true;
      }
  }

  render() {
    return (
      <div className="gallery-root">
        {this.state.images.map((dto , i) => {
          return <Image key={'image-' + dto.id+ i.toString()} dto={dto} galleryWidth={this.state.galleryWidth}/>;
        })}
      </div>
    );
  }
}

I am keeping tag initial value to empty as you are not doing anything with value art.

Please try with below code

class App extends React.Component {
  static propTypes = {
  };

  constructor() {
    super();
    this.timeout =  0;
    this.state = {
      tag: '',
      callGallery: false
    };
  }


  doSearch = (event) => {
    this.setState({tag: event.target.value, callGallery: false});
  }

  handleSearch = () => {
     this.setState({
        callGallery: true
     });
  }

  render() {
    return (
      <div className="app-root">
        <div className="app-header">
          <h2>Gallery</h2>
          <input className="input" onChange={event => this.doSearch(event)} value={this.state.tag}/>
         <input type="button" value="Search" onClick={this.handleSearch} />
        </div>
        {this.state.callGallery && <Gallery tag={this.state.tag}/>}
      </div>
    );
  }
}

export default App;

onChange handler is just fine but you need to bind the setTimeout to render context.Currently,it is referring to window context.And the code as follows

   doSearch(event){
        var searchText = event.target.value; // this is the search text
        if(this.timeout) clearTimeout(this.timeout);
        this.timeout = setTimeout(function(){
                         this.setState({
                             tag: event.target.value
                         }) 
                       }.bind(this),500);
      }

This is because you haven't bound this to your method.

Add the following to your constructor:

this.doSearch = this.doSearch.bind(this);

Also, you don't need the fat arrow notation for onChange. Just do:

onChange={this.doSearch}