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Can you use the Array.prototype.find() to check against more than one condition to find something?

I am creating a calculator app in JS and I got it to work by using the mouse to click buttons on the screen so I am now integrating the use of the keyboard. Long story short, in part of my functionality before the keyboard was being used I was using the find property on an array to find the last operator clicked that was NOT the = btn and it worked perfectly fine:

lastOperatorThatIsNotEqual = operatorArray.reverse().find(e => e !== "=")

Now that I am using the keyboard, when I click enter I want it to be the equivalent of clicking the = btn so I tried doing it this way using an external function and an if/else statement

function test(e) {
    if (e !== 'Enter') {
        return e
    } else if (e !== '=') {
        return e
    } else {
        console.log('wrong')
    }
}

lastOperatorThatIsNotEqual = operatorArray.reverse().find(test)

However the above does not work. If I remove the else if portion so it's just e !== 'Enter' or e !== '=' then it works fine but I can't have both in there at the same time. I figure it's probably more efficient to have it check that way instead of doing two functions but can't figure out why this isn't working.

Any suggestions are much appreciated. Thanks!

7 months ago · Juan Pablo Isaza

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Return a boolean from find. Try this:

function test(e) {
  return e === 'Enter' || e === '='
}

7 months ago · Juan Pablo Isaza Report

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Accepted Answer · 2022-07-13T01:53:35.665Z

Your conditions are messed up. This

if (e !== 'Enter') {
    return e
} else if (e !== '=') {
    return e
}

will invariably result in one of those branches being fulfilled. If the first condition isn't fulfilled, then e is 'Enter', so e !== '=' is fulfilled.

You should also return a boolean (or a value that's known to be truthy or falsey) from a .filter callback - don't return the value being iterated over, because if the value is falsey, it won't be included in the resulting array.

const lastOperatorThatIsNotEqual = operatorArray.reverse().find(
  e => e !== "=" && e !== 'Enter'
)

or

function test(e) {
    if (e === 'Enter') {
        return false;
    }
    if (e === '=') {
        return false;
    }
    return true;
}

lastOperatorThatIsNotEqual = operatorArray.reverse().find(test)