JS：为什么当我点击按钮时没有提示信息？

Question

I try the code below but when i click button does not show the alert message!

let clickButton = document.getElementsByClassName("buttonClass");

clickButton.onclick = clickFunc;

function clickFunc(){ alert("hello")};

console.log(clickButton);

i create buttons with document.createElement

console log return this

I have try:

1. To choose only one button like this let clickButton = document.getElementsByClassName("buttonClass")[1]; but nothing

2. Also i have try to get element by tagname, loop with a length of buttons, and addeventlistener, but nothing again

Answer 1

 let buttons = document.getElementsByClassName("buttonClass"); for (var i = 0; i < buttons.length; i++) { buttons.item(i).addEventListener('click', function(e) { alert("hello"); }); }

 <button type="button" class="buttonClass">button 1</button> <button type="button" class="buttonClass">button 2</button> <button type="button" class="buttonClass">button 3</button> <button type="button" class="buttonClass">button 4</button> <button type="button" class="buttonClass">button 5</button>

Since your targeting by class, you get an array of elements. So you have to iterate and attach click events to each element as show below;

let buttons = document.getElementsByClassName("buttonClass");
for (var i = 0; i < buttons.length; i++) {
  buttons.item(i).addEventListener('click', function(e) {
    alert("hello");
  });
}