How to remove object from Array in ReactJS after click event

Question

I'm building little app in React and I have a problem to remove and object from Array after I click on icon.

I have form with inputs and when user fill this inputs and click on a button then inputs will into an array. I have array in a state and the default is empty array.

const [attendees, setAttendees] = useState([]);

I have a function for delete a object from array after I click on icon

const deleteAttendee = (attendee) => {
    setAttendees({
      attendees: attendees.filter(
        (element) => element.firstName !== attendee.firstName
      ),
    });
  };

but there is a problem when I clicked on icon I get an error. That map is not a function.

I have in another component map function for rendering each user from the inputs

<div className="attendee-container">
      {attendees.map((_attendee, index) => {
        return (
          <div key={index}>
            <div onClick={() => deleteAttendee(_attendee)}>{trashAltIcon}</div>
            <h3>
              {index + 1}. {_attendee.firstName} {_attendee.lastName} (
              {_attendee.age})
            </h3>
          </div>
        );
      })}
    </div>

Thank you in advance for your help.

Moshe Sommers · Accepted Answer · 2020-09-18 18:55:03Z

2

When using setState you pass in the full state object like you'r doing. However when using useState hooks the setState functions takes in just that value.

Check out these docs for understanding the difference between setState and updating state with useState hook

setAttendees takes in an array so your handler should be

const deleteAttendee = (attendee) => {
   //Pass in filtered array as new state for attendees
   setAttendees( attendees.filter((element) => element.firstName !== attendee.firstName);
};

edited Sep 18, 2020 at 18:55

answered Sep 18, 2020 at 17:46

Moshe Sommers

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Comments

Anthony Gedeon · Accepted Answer · 2020-09-18 18:46:54Z

setAttendees comes with a parameter that allows you to have the previous state.

Here's what I did to your deleteAttendee function

const deleteAttendee = (event) => {

   const attendeeId = event.target.dataset.id;

   setAttendees((previousState) => previousState.filter((attendee) => attendee.id !== attendeeId))

};

I am using the previous state and updating that instead and instead of removing the first name I am instead removing matching ids

Here's what the jsx looks like

return (
<div className="App">
  {attendees.map((_attendee, index) => {
    return (
      <div key={_attendee.id}>
        <div data-id={_attendee.id} onClick={(event) => deleteAttendee(event)}>trash</div>
        <h3>
          {index + 1}. {_attendee.firstName} {_attendee.lastName} (
          {_attendee.age})
        </h3>
      </div>
    );
  })}
</div>

);

I am using a data-id attribute so whenever the user clicks on the trash icon, I can pass that event into the deleteAttendee, get the value from the attribute and filter the array out if it matches. I made this change because I saw that you was filtering based on names, what if two attendees had the same name?

Initial state of attendees

const [attendees, setAttendees] = useState([
   {
     id: 'tskdh3-3dfdgg-23ds-23dfsdd-2332',
     firstName: 'bob',
     lastName: 'jeo',
     age: 73
  },
  {
     id: 't3-3dfdgg-23ds-23dfsdd-2332',
     firstName: 'bob',
     lastName: 'woah',
     age: 43
  },
  {
     id: 'bsd233-33dfg-3ds-2f3fsdd-2dfdf',
     firstName: 'bob',
     lastName: 'yum',
     age: 23
   }
]);

For random ids to be generated, you an use an npm package called uuid, it generates unique ids.

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How to remove object from Array in ReactJS after click event

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Comments

Here's what I did to your deleteAttendee function

Here's what the jsx looks like

Initial state of attendees

Comments

Your Answer

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2 Answers 2

Comments

Here's what I did to your deleteAttendee function

Here's what the jsx looks like

Initial state of attendees

Comments

Your Answer

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