javascript - Why when I clicked on subtract or multiply button still doing the add function?

Question

My if statements don't work because I said to the statements to make subtract, if subtractOp (subtract button is clicked) were click and this operator still doing add function.

let firstValue;
let secondValue;

addOp.addEventListener('click', function() {
    firstValue = Number(outPut.innerText);
    outPut.innerText = '';
});

subtractOp.addEventListener('click', function() {
    firstValue = Number(outPut.innerText);
    outPut.innerText = '';
});

multiplyOp.addEventListener('click', function() {
    firstValue = Number(outPut.innerText);
    outPut.innerText = '';
});

equals.addEventListener('click', function() {
    secondValue = Number(outPut.innerText);
    if(addOp) {
        outPut.innerText = add(firstValue, secondValue);
        console.log(add(firstValue, secondValue));
    } else if(subtractOp) {
        outPut.innerText = subtract(firstValue, secondValue);
        console.log(subtract(firstValue, secondValue));
    } else if(multiplyOp) {
        outPut.innerText = multiply(firstValue, secondValue);
        console.log(multiply(firstValue, secondValue));
    }
});

question from:https://stackoverflow.com/questions/65516654/why-when-i-clicked-on-subtract-or-multiply-button-still-doing-the-add-function

Answer 1

That's because your if/else statement in the equals handler is wrong.

    if(addOp) {
        outPut.innerText = add(firstValue, secondValue);
        console.log(add(firstValue, secondValue));
    } else if(subtractOp) {
        outPut.innerText = subtract(firstValue, secondValue);
        console.log(subtract(firstValue, secondValue));
    } else if(multiplyOp) {
        outPut.innerText = multiply(firstValue, secondValue);
        console.log(multiply(firstValue, secondValue));
    }

if(addOp) always returns true because addOp is an HTML element. You need to add booleans to determine what operation you wish to perform.