How to use a function in addEventListerner

Question

I am learning the basics and trying to play around with JS. My question is how can I use a function written outside addEventListener. Right now I am using the following code:

ageCalculatorButton.addEventListener('click',function (event){
    var birthYear= prompt("What year you were born");
})

Now let's suppose I am trying to reuse a piece of code, how will I call the function from addEventListener. I am trying to accomplish the following:

ageCalculatorButton.addEventListener('click',ageInDays())


function ageInDays(){
    var birthYear= prompt("What year you were born");
}

Is it even possible or am I just hungup in solving an insolvable problem.

ageCalculatorButton.addEventListener('click',ageInDays) not ageCalculatorButton.addEventListener('click',ageInDays()) — Arif Khan, May 19 '22 at 05:09

score 1 · Answer 1 · answered May 19 '22 at 05:12

Firstly, you can reuse functions from outside.

try it like this:

ageCalculatorButton.addEventListener('click',ageInDays)


function ageInDays(){
    var birthYear= prompt("What year you were born");
}

Or even you can pass in the prompt function like this:

ageCalculatorButton.addEventListener('click',ageInDays(prompt))


function ageInDays(func){
    return function(){
        var birthYear=func("What year you were born");
    }
}

How to use a function in addEventListerner

1 Answers1