Can I add array in class in JavaScript?

Question

I am very new to JavaScript, and I tried to add array to my class to save some data:

class ListOfItems {
  let listOfItems = []
  addItem(item) {
    listOfItems.push(item);
    console.log(listOfItems);
  }
}

const lOi = new ListOfItems();

lOi.addItem(10);

But I get this error:

SyntaxError: Unexpected identifier

I don't know if it is allowed to have variables in class. What can I do? I just want to have array of every added item.

I'm not sure the let is needed? Remove the let, then it can be accessed by this.listOfItems — evolutionxbox
– evolutionxbox, Commented Mar 25, 2021 at 12:31
create a constructor and initialize the array, then use this.listOfItems in the method to push — Shyam Kumar
– Shyam Kumar, Commented Mar 25, 2021 at 12:32
Introduce a constructor and initialise this.listOfItems = [] inside of that. — Rajaprabhu Aravindasamy
– Rajaprabhu Aravindasamy, Commented Mar 25, 2021 at 12:32
Please at least read developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… preferably a full javascript tutorial, that includes a section about classes. — ASDFGerte
– ASDFGerte, Commented Mar 25, 2021 at 12:37

Rajaprabhu Aravindasamy · Accepted Answer · 2021-03-25 12:38:59Z

1

You can simply write. I hope it worked for you.

class ListOfItems
{
  constructor(listOfItems) {
    this.listOfItems = [];
  }

  addItem(item)
  {
    this.listOfItems.push(item);
    console.log(this.listOfItems);
  }
}

edited Mar 25, 2021 at 12:38

Rajaprabhu Aravindasamy

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answered Mar 25, 2021 at 12:33

Salman Bukhari

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2 Comments

Anz Over a year ago

I tried it, but now I get error: listOfItems is not defined

noggin182 Over a year ago

@Anz, for console.log it should be console.log(this.listOfItems)

Not A Robot · Accepted Answer · 2021-03-25 12:55:08Z

0

You need constructor for creating and initializing an object of that class.

Instead of

let listOfItems = [];

Use constructor to initialize the array.

constructor(listOfItems) {
  this.listOfItems = [];
}

Code:

class ListOfItems {
  constructor(listOfItems) {
    this.listOfItems = [];
  }

  addItem(item) {
    this.listOfItems.push(item);
    console.log(this.listOfItems);
  }
}

const lOi = new ListOfItems();

lOi.addItem(10);
lOi.addItem(20);

edited Mar 25, 2021 at 12:55

answered Mar 25, 2021 at 12:44

Not A Robot

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