具有相同类的多个按钮的单击事件上的Javascript

Question

I have a few buttons across a site I am building, certain buttons have one class while others have another. What I am trying to do is find the best way to find the clicked button without having an event listener for each individual button. I have come up with the below 2 for loops to find all the buttons with class button-1 and class button-2. Being fairly new to javascript i just don't want to get into bad habits so would appreciate any advice on the best way to achieve this.

<section>
  <div class="button--1"></div>
  <div class="button--1"></div>
  <div class="button--2"></div>
</section>

<section>
  <div class="button--2"></div>
  <div class="button--1"></div>
  <div class="button--2"></div>
</section>

 var button1 = document.querySelectorAll('.button--1');
    var button2 = document.querySelectorAll('.button--2');

    for (var a = 0; a < button1.length; a++) {    
        button1[a].addEventListener('click',function(){
            //do something
        });
    }

    for (var b = 0; b < button2.length; b++) {
        button1[b].addEventListener('click',function(){
            //do something
        });
    }

Answer 1

If you plan to have multiple other classes like button--3 , …4 … …15 ,
You must want to target all div elements which class starts ( ^= ) with "button":

(Note that you can do it in the CSS too!)

 var allButtons = document.querySelectorAll('div[class^=button]'); console.log("Found", allButtons.length, "div which class starts with “button”."); for (var i = 0; i < allButtons.length; i++) { allButtons[i].addEventListener('click', function() { console.clear(); console.log("You clicked:", this.innerHTML); }); }

 /* Some styling */ section { margin: 8px 0; border: 1px solid gray; } section div { border: 1px solid lightgray; display: inline-block; margin-left: 8px; padding: 4px 8px; width: 30px; } section div[class^=button] { background: lightgray; cursor: pointer; }

 <span>You can click on the buttons:</span> <section> <div class="button--1">s1-1</div> <div class="button--2">s1-2</div> <div class="button--3">s1-3</div> <div class="button--4">s1-4</div> </section> <section> <div class="button--1">s2-1</div> <div class="button--2">s2-2</div> <div class="button--3">s2-3</div> <div class="button--4">s2-4</div> </section> <section> <div class="not-a-button">not1</div> <div class="not-a-button">not2</div> <div class="not-a-button">not3</div> <div class="not-a-button">not4</div> </section>

Hope it helps.

Answer 2

Try using event delegation

 (function() { document.body.addEventListener("click", clickButtons); // ^ one handler for all clicks function clickButtons(evt) { const from = evt.target; console.clear(); if (!from.className || !/button--\\d/i.test(from.className)) { return; } // ^check if the element clicked is one of the elements you want to handle // if it's not one of the 'buttons', do nothing console.log("you clicked " + from.classList); } }())

 .button--1:before, .button--2:before { content: 'BTTN['attr(class)']'; } .button--1, .button--2 { border: 1px solid #999; background: #eee; width: 220px; padding: 3px; text-align: center; }

 <section> <div class="b1 button--1 section1"></div> <div class="b2 button--1 section1"></div> <div class="b3 button--2 section1"></div> </section> <section> <div class="b4 button--2 section2"></div> <div class="b5 button--1 section2"></div> <div class="b6 button--2 section2"></div> </section>

Answer 3

You can use multiple selectors in the string of querySelctorAll() by separating them with a ,

 var button1 = document.querySelectorAll('.button--1'); var button2 = document.querySelectorAll('.button--2'); var allButtons = document.querySelectorAll('.button--1, .button--2'); console.log(button1.length); console.log(button2.length); console.log(allButtons.length);

 <section> <div class="button--1"></div> <div class="button--1"></div> <div class="button--2"></div> </section> <section> <div class="button--2"></div> <div class="button--1"></div> <div class="button--2"></div> </section>

Answer 4

The click event is fired when a pointing device button (usually a mouse's primary button) is pressed and released on a single element.

This documentation will help you to understand how it works MDN - Click event

Answer 5

My suggestion is to use jQuery so that you can do it something like this:

$(document).on('click', '.button--1', function() {
   // Do something
});

$(document).on('click', '.button--1', function() {
   // Do something
})

But a clean approach for pure Javascript is to create a function that binds a callback for the event.

function bindEvent(callback, eventType, targets) {
   targets.forEach(function(target) {
     target.addEventListener(eventType, callback);
   });
};


var button1 = document.querySelectorAll('.button--1');
var button2 = document.querySelectorAll('.button--2');

bindEvent(function() {
   // do something
}, 'click', button1);

bindEvent(function() {
   // do something
}, 'click', button2);