Testing State Objects in React

Question

I've seen this question and it's helped with my understanding of how to set state correctly, but I'm struggling with the correct format of testing state based on a variable.

For example, I have this setState function call with a newItem variable:

addToSandwich(newItem){

    setState(prevState => {
        return { sandwichItems: {...prevState.sandwichItems, [newItem]: true} };
    });

}

And assuming the current state looks like this:

sandwichItems: {
    meat: true,
    cheese: true,
    tomato: false
}

With var newItem = "tomato";

It would result in this:

sandwichItems: {
    meat: true,
    cheese: true,
    tomato: true
}

But I am unable to test for newItem with:

var newItem = "tomato";

if (this.state.sandwichItems.newItem === true) {//whatever}

I would have to do:

if (this.state.sandwichItems.tomato === true) {//whatever}

How do I test for a value in state based on a variable's value?

If you want to view the state from your browser, I'd recommend checking out the React DevTools — Jon Warren
– Jon Warren, Commented Aug 1, 2018 at 19:12
@JonWarren I currently use the React DevTools and it's been one of the most useful tools for my web dev projects — Jaich
– Jaich, Commented Aug 1, 2018 at 19:15

Hoyen · Accepted Answer · 2018-07-16 19:04:56Z

1

This is what you want:

var newItem = "tomato";
if(this.state.sandwichItems[newItem] === true { }

answered Jul 16, 2018 at 19:04

Hoyen

2,5291 gold badge14 silver badges13 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Jaich Over a year ago

This worked, thank you! I'm going to leave the question up for a bit before accepting, but this is the answer I was looking for.

Jaich Over a year ago

Just by chance, would you know the syntax to go another object deeper? As if tomato was an object as well? Would it be (this.state.sandwichItems[newItem][value])?

Hoyen Over a year ago

@Jaich that looks right. But you would need to show me an example of the object.

Collectives™ on Stack Overflow

Testing State Objects in React

1 Answer 1

3 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related