Matching values of arrays in Java script

Question

I have an event-listener that adds a new item to an array every time I click an image. How can I check if the item newly-added to the array matches an item in the other array?

let a = ['a', 'b', 'c', 'd']

let b = []

grid.addEventListner('click', (e) =>{

let clicked = e.target

b.push(clicked)

// Here is where I want to check if the variable "clicked"
// which is pushed in to the b array matches 
// the value on the same position in the a array. So for
// every click if its right I add a // green class and if
// its not I add a red class and finish the possibility
// to play.

})

Hope I was able to explain the problem:)

Answer 1

If I understand correctly you want to check if the new item in b is equal to the item at the same position in a. You can this like so:

if (a[b.length - 1] === clicked) {
        //set green
} else {
        //set red
}

You can replace clicked with b[b.length - 1] if, when you are checking, clicked is out of scope.

If you are wanting to see if any item in a matches the clicked new item in b you can use the array.find method.

if(a.find( el => el === clicked)) {
   // set green
} else {
   // set red
}

Based on where the comments in the code are, it appears you want this logic to run inside that function. Which is why I have added a simple if block here

Answer 2

You can use Array.find to check for the existence of an element in some Array . An example:

 const someArray = ['a', 'b', 'c', 'd']; const newElem = 'a'; const newElem2 = 'hello'; console.log(someArray.find(elem => elem === newElem)? `${newElem} exists:`; `${newElem} is new.`). if (;someArray.find(elem => elem === newElem2)) { someArray.push(newElem2); } console.log(JSON.stringify(someArray));

Answer 3

You don't need another array to record the validity of the clicks; just a counter.

 const buttonWrapper = document.getElementById('button_wrapper'); const a = ['a', 'b', 'c', 'd'].map(l => document.getElementById(`button_${l}`)); let counter = 0; buttonWrapper.addEventListener('click', e => { if (e.target.tagName === "BUTTON") { if (e.target === a[counter]) { buttonWrapper.classList.remove('red') buttonWrapper.classList.add('green'); counter = (counter + 1) % a.length; } else { buttonWrapper.classList.remove('green') buttonWrapper.classList.add('red'); counter = 0; } } });

 #button_wrapper { display: table; padding: 10px; border: 4px solid #000; } #button_wrapper.red { border-color: red; } #button_wrapper.green { border-color: green; }

 <div id="button_wrapper"> <button id="button_a">Button A</button> <button id="button_b">Button B</button> <button id="button_c">Button C</button> <button id="button_d">Button D</button> </div>