如何在单击时将 function 中的变量作为全局变量返回

Question

I would like to return "a=5" variable from the function on click as a global variable and then alert it. Can you please only reply with javascript codes and not jquery. I am trying to understand javascript.

 function startBtn() { var a = 5; return a; } document.getElementsByName("submit-button")[0].addEventListener("click", startBtn); // var test = startBtn(); //Does not work as I want. I want to pass this as a global variable. // alert(test); //Does not work as I want

 <input class="submit-btn" type="submit" name="submit-button" value="Start">

Thanks.

Answer 1

Get the value of the function when the user click on the button and alert inside clickListener .

As per your code snippet you are getting the value of the startBtn function outside of the click listener and alerting it also give 5 , but you need to get the value and alert that value only after the user click on the button not when JS is compiled.

 function startBtn() { var a = 5; return a; } document.getElementsByName("submit-button")[0].addEventListener("click", () => { var test = startBtn(); alert(test); }); var test = startBtn(); alert(test);

 <input class="submit-btn" type="submit" name="submit-button" value="Start">

Answer 2

if you want to alert a from js function just insert the alert function on your startBtn function like this

 function startBtn() { var a = 5; alert(a); } document.getElementsByName("submit-button")[0].addEventListener("click", startBtn); // var test = startBtn(); //Does not work as I want // alert(test); //Does not work as I want

 <input class="submit-btn" type="submit" name="submit-button" value="Start">