Matching values of arrays in Java script-CodePudding

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 :)

CodePudding user response：

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

CodePudding user response：

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));

CodePudding user response：

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>