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Let's build a search bar in React!

Tim Smith on September 11, 2018

The original version of this article can be found here. I know, I know...another task app... Hear me out though! We are going to build a task app...

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Zachary Becker • Sep 12 '18

Thanks for the article.

You addItem/removeItem has a fairly unlikely race condition in it.

You are reading the list from the state, modifying it, then using this.setState. However, this.setState does not update the state immediately.

In theory, addItem could get called twice in quick succession, and you would lose one of the items added. For example with this possible ordering of events:

Initial List ["a", "b", "c"]
addItem Called with "d", modified list ["a", "b", "c", "d"], setState called
addItem called with "e", modified list ["a", "b", "c", "e"], setState called
State is updated with ["a", "b", "c", "d"]
State is updated with ["a", "b", "c", "e"]

Just something to keep in mind.

Tim Smith • Sep 12 '18

Interesting. How would you suggest preventing that issue in a project like this?

Zachary Becker • Sep 12 '18 • Edited

Use call back format for setState.

this.setState(state => {
  const list = state.list;
  /* modify list */;
  return {
    list: modifiedList
  };
});

David Async • Sep 12 '18 • Edited

Great tutorial, but why not use facebook cra instead ?

Sung M. Kim • Sep 12 '18

If cra is your choice, you can try c-r-a-p 💩-create-react-app-parcel 😃

Tim Smith • Sep 12 '18

I have not heard of this. It looks cool though. Thanks for the link!

Tim Smith • Sep 12 '18

It’s really personal preference, but to be honest I haven’t used create-react-app in a while and forgot it existed.

Miguel Ruiz • Sep 12 '18

At the end It's better to make it your own way. create-react-app is for fast dev or examples but not for real projects.

Jason Espin • Sep 12 '18

That's not necessarily true. I know plenty of enterprit level projects that use React that were created with CRA. As long as you configure and secure it, it's the best solution for making a start on a React project.

machy44 • Sep 14 '18 • Edited

Nice Article.

When I use getDerivedStateFromProps() in same way you use componentWillReceiveProps() in List component searching doesn't work.

static getDerivedStateFromProps(nextProps) {
return {
filtered: nextProps.items
};
}

I didn't know that getDerivedStateFromProps is called every time we setState(). Link for lifecycles projects.wojtekmaj.pl/react-lifecy....

I wanted to share this thought with you cause I didn't give enough attention about differences between componentWillReceiveProps and getDerivedStateFromProps and IMHO this is kind of important.

Tim Smith • Sep 14 '18

This is awesome! Thanks for the link!

machy44 • Sep 14 '18

Np. Thank you for the article

Richard • Jun 14 '20 • Edited

Hi there,

Really liked your tutorial Tim! <3 I thought I try all of that with functional components and this is what I got (feel free to correct me - I'm kinda rookie in webdev). Seems working though!

Minor changes I made:

used functional components instead of class components. Therefore used React.useState() for storing variables in the state.
input element for adding new todo is a controlled component and handled also in the state. Found this approach more "react-ish".
for deleting a todo I also used filter() method - seems more handy for me.
some naming changes

App.js

// App.js

import React, { useState, Fragment } from "react";
import List from "./List";

const App = () => {
  const [userInput, setUserInput] = useState("");
  const [list, setList] = useState([
    "walk the dog",
    "buy the milk",
    "learn some code"
  ]);

  // userinput is controlled by the App component
  const handleChange = e => {
    setUserInput(e.target.value);
  };

  const addItem = e => {
    if (userInput !== "") {
      setList([...list, userInput]);
      setUserInput("");
    }
  };

  const removeItem = item => {
    const updatedList = list.filter(listItem => listItem !== item);
    setList(updatedList);
  };

  return (
    <Fragment>
      <List list={list} removeItem={removeItem} />
      <hr />
      <form>
        <input
          placeholder="Something that needs to be done..."
          value={userInput}
          onChange={handleChange}
        />
        <button type="button" onClick={addItem}>
          {'Add Item'}
        </button>
      </form>
    </Fragment>
  );
}

export default App;

List component:

// List.js

import React, { useState, useEffect, Fragment } from "react";

const List = ({ list, removeItem }) => {
  const [filtered, setFiltered] = useState([]);

  useEffect(() => {
    setFiltered(list);
  }, [list]);

  const handleChange = e => {
    let currentList = [];
    let newList = [];

    if (e.target.value !== "") {
      currentList = list;
      newList = currentList.filter(item => {
        const lc = item.toLowerCase();
        const filter = e.target.value.toLowerCase();
        return lc.includes(filter);
      });
    } else {
      newList = list;
    }
    setFiltered(newList);
  };

  return (
    <Fragment>
      <input 
        type="text" 
        placeholder="Search..." 
        onChange={handleChange} 
      />
      <ul>
        {filtered.map((todo, i) => (
          <li key={`${todo}-${i}`}>
            {todo} &nbsp;
            <span onClick={() => removeItem(todo)}>x</span>
          </li>
        ))}
      </ul>
    </Fragment>
  );
};

export default List;

default create-react-app index.js...

// index.js

import React from "react";
import ReactDOM from "react-dom";

import App from "./App";

const rootElement = document.getElementById("root");
ReactDOM.render(
  <React.StrictMode>
    <App />
  </React.StrictMode>,
  rootElement
);

Scott Bergler • Jun 23 '19

"Fair warning: This part may get a bit abstract, so do your best to stick with me. If I don't explain well enough or you're struggling with it, leave a comment and I'll try to help you get it." ~ T. Smith

I love the generous spirit and the acknowledgement that sometimes what we think we're say/writing is not what is heard/understood.

Victor Tolbert • Sep 14 '18

Thanks for the article.

FYI, I don't see the instructions to modify the package.json to include the start script.

Tim Smith • Sep 14 '18

Thanks! I have added the piece about scripts in the package.json file.

Ben Sinclair • Sep 12 '18

There's a typo: mkdir search-tasks && $_ should be mkdir search-tasks && cd $_

Tim Smith • Sep 12 '18

Fixed. Thank you!

Sagar • Sep 12 '18

Hi Tim,

I found typo error at Next we need to install the necessary packages to our package. => Next we need to install the necessary packages to our project

Tim Smith • Sep 12 '18

Corrected. Good catch. It sounded like I was trying to be xhibit or something.

Maynard J. Hartman, Jr. • Apr 17 '19

Great Article Thanks...

Tim Smith • Apr 18 '19

No problem. I’m glad it was helpful!

Dennis savai • Oct 22 '18

If you get an error when importing like --> import 'bulma/bulma' use --> import 'bulma/css/bulma.css'

Ankush Chauhan • Aug 7 '21

how to add not found text when the user didn't find any related results?

view here - loom.com/share/59eed867b4594ace89e...

Anas Khan • Nov 24 '20

Hey! nice article. but how do we implement search via using two keywords. like i have rows of some information. i want to search using keywords age and gender. any idea?