如何将多个事件处理程序添加到同一事件？

Question

I'm new to JavaScript and I'm trying to register 2 event handlers to the same event from two different functions, but no matter what I try one event handler overrides the other. Is there any way that I can register multiple event handlers from different functions?

In the code bellow I try to register two event handlers by pressing two buttons, but the handlers override each other.

 <p id="text">text</p> <p id="text1">text1</p> <button id="myBtn">text</button> <button id="myBtn1">text1</button> <script> document.getElementById("myBtn").addEventListener("click", foo); document.getElementById("myBtn1").addEventListener("click", bar); function foo() { var target = document.getElementById("text"); document.body.onkeypress = function(e){ animateElem(target); } } function bar() { var target = document.getElementById("text1"); document.body.onkeypress = function(e){ animateElem(target); } } function animateElem(elemFound){ var start = 0.3; var increment = 0.3; var id = setInterval(allOpacity, 100); function allOpacity() { if (start > 3) { clearInterval(id); elemFound.style.opacity = 0.5; } else { start = start + increment; elemFound.style.opacity = start % 1; } } } </script> 

Answer 1

You should use addEventListener() instead of onkeypress

addEventListener allows adding more than a single handler for an event.

document.body.onkeypress = function(e){...} will override the other function.

 <p id="text">text</p> <p id="text1">text1</p> <button id="myBtn">text</button> <button id="myBtn1">text1</button> <script> document.getElementById("myBtn").addEventListener("click", foo); document.getElementById("myBtn1").addEventListener("click", bar); function foo() { var target = document.getElementById("text"); document.body.addEventListener('keypress',(e)=>{ animateElem(target); }) } function bar() { var target = document.getElementById("text1"); document.body.addEventListener('keypress',(e)=>{ animateElem(target); }) } function animateElem(elemFound){ var start = 0.3; var increment = 0.3; var id = setInterval(allOpacity, 100); function allOpacity() { if (start > 3) { clearInterval(id); elemFound.style.opacity = 0.5; } else { start = start + increment; elemFound.style.opacity = start % 1; } } } </script>