I'm building a game where a player purchases and sells items. On purchase I need to add the purchased item to the "player's bag." I want to check if the item already exists in the "player's bag" and if so I want to update that item. If it isn't there already I want to add it.

I've got the function to add it if it doesn't exist already down but I'm having problems checking to see if it exists and then updating it if it does. I've tried using .find and .filter to loop through the state but they both throw errors that ".find/.filter is not a function."

Here's the function currently:

   addItem = (item, quantity, totalPrice) => {
        console.log(item);
     this.setState({
        funds: this.state.funds - totalPrice,
    });
            let items = this.state.playerItems;
    let itemIsInBag = items.filter(item => item.name.indexOf(item.name) >= 0); 

     //* I also used "let itemIsInBag = items.find(matchingItem => matchingItem.name == item.name);" both returned the not a function error

           if (itemIsInBag) {
        const newQuantity = this.matchingItem.quantity + quantity;
        const newPrice = (this.matchingItem.price + totalPrice) / newQuantity;

        const newItem = {
            name: item.name,
            price: newPrice,
            quantity: newQuantity,
                        }
       
    } else {
        const newItem = {
            name: item.name,
            price: totalPrice,
            quantity: quantity,
                        }
        const playerItems = this.state.playerItems.concat(newItem);
        return {
            playerItems
        };
    };
}

Any ideas about what I'm doing wrong or that would be a better way would be greatly appreciated.

Hi All,

I am doing a trivia to learn react and I have this problem. How to know which particular item of the array was clicked?

I thought that adding index would help but seems like that's not enough (console.log shows all the answers for the question)?

Here's my code for now:

<div> <h2>{this.props.trivia.question}</h2> </div> <div> **{this.props.trivia.answers.map((triviaAns, index)=>** <li **key={triviaAns.index}** onClick={()=>this.props.onClick(id)} \> {quizAnswer.ans} **{console.log(\[triviaAns.index\])}**

</li>

)}

</div>

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