How to addEventListener to Multiple Elements in a Single Line

Event Bubbling is the important concept in javascript, so if you can add event on DOM directly, you can save some lines of code, no need for looping :

document.addEventListener('click', function(e){
  if(e.target.tagName=="BUTTON"){
   alert('BUTTON CLICKED');
  }
})

If you don't want to have a separate elementsArray variable defined you could just call forEach from an unnamed array with the two elements.

[ Element1, Element2 ].forEach(function(element) {
   element.addEventListener("input", function() {
      this function does stuff
   });
});

One line

document.querySelectorAll("whatever").forEach(elem => elem.addEventListener("input", fn))

I cannot claim credit for this solution but I found a great solution here.

    var theParent = document.querySelector("#theDude");
    theParent.addEventListener("click", doSomething, false);

    function doSomething(e) {
        if (e.target !== e.currentTarget) {
            var clickedItem = e.target.id;
            alert("Hello " + clickedItem);
        }
        e.stopPropagation();
    }

Example:

const element1 = document.querySelector("#element1");
const element2 = document.querySelector("#element2");

[element1, element2].map(element => element.addEventListener("click", function() {
  /*some expressions :)*/
}))

If you are using Javascript through Electron and you have a list of buttons, you can use this code to add an EventListener to each button. I'm actually using this method because classical Javascript methods (map(), forEach() ...) weren't supported anymore.

let buttons = document.getElementsByClassName('className');
for(let i = 0; i<buttons.length; i++){
   buttons[i].addEventListener('click', () => {
      /*put your code here*/
   });
}

Maybe it will help you

let all_btn = document.querySelectorAll("button");
all_btn.forEach(function(btn) {
    btn.addEventListener("click", function() {
        console.log(this.innerHTML + " is clicked")
    });
});

// one line code
// let all_btn=document.querySelectorAll("button");all_btn.forEach(function(n){n.addEventListener("click",function(){console.log(this.innerHTML+" is clicked")})});

<button>button 1</button>
<button>button 2</button>
<button>button 3</button>

The easiest way so far I've learned.

// Get an array of buttons from the page
var buttons = document.querySelectorAll(".btns");

// Loop through the resulting array
for(var i = 0; i < buttons.length; i++){
  buttons[i].addEventListener("click", function() {
    console.log("Hello World");
  });
}

I always recommend delegation - if the inputs are in the same container, then you can do this

window.addEventListener("DOMContentLoaded", function() { // on page load
  document.getElementById("inputContainer").addEventListener("input", function(e) { // passing the event
    const tgt = e.target;
    const id = tgt.id;
    console.log("You typed in",id)
  });
});

<div id="inputContainer">
  <h1>Start typing or paste</h1>
  <input id="element1">
  <input id="element2">
</div>

Example for initializing one unique event listener specific to each element.

You can use the slider to show the values in realtime, or check the console.

On the <input> element I have a attr tag called data-whatever. You can use that to customize each event listener further.

sliders = document.querySelectorAll("input");
sliders.forEach(item=> {
  item.addEventListener('input', (e) => {
    console.log(`${item.getAttribute("data-whatever")} is this value: ${e.target.value}`);
    item.nextElementSibling.textContent = e.target.value;
  });
})

.wrapper {
  display: flex;
}
span {
  padding-right: 30px;
  margin-left: 5px;
}
* {
  font-size: 12px
}

<div class="wrapper">
  <input type="range" min="1" data-whatever="size" max="800" value="50" id="sliderSize">
  <em>50</em>
  <span>Size</span>
  <br>
  <input type="range" min="1" data-whatever="OriginY" max="800" value="50" id="sliderOriginY">
  <em>50</em>
  <span>OriginY</span>
  <br>
  <input type="range" min="1" data-whatever="OriginX" max="800" value="50" id="sliderOriginX">
  <em>50</em>
  <span>OriginX</span>
</div>

If you have a DOM Collection, I suggest you to use the for ... of

In this MDN web doc you can see the details, but, for example, if you have:

HTMLCollection(6) [a.example, a.example, a.example, a.example, a.example, a.example]

You can:

let arrayElements = document.getElementsByClassName('example');
for (let element of arrayElements) {
    element.addEventListener("click", function() {
        console.log('Whoa! You clicked me')
    });

And ta-dah! ;)

Here's what I used to set a click evenhandler on every span in my HTML (each span contains an emoji). When you click it, it will alert the emoji in the sample code.

Array.from(document.querySelectorAll("span")).map(element => element.addEventListener("click", function() {
  alert(element.innerHTML);
}));

div{background: whitesmoke;}
span{ont-size:x-large;
    cursor:pointer;}

<div>
  <span>&#128512;</span>
  <span>&#128513;</span>
  <span>&#128514;</span>
  <span>&#128515;</span>
  <span>&#128516;</span>
  <span>&#128517;</span>
  <span>&#128518;</span>
  <span>&#128519;</span>
  <span>&#128520;</span>
  <span>&#128521;</span>
  <span>&#128522;</span>
  <span>&#128523;</span>
</div>

First include jQuery then after you have included, add this script below.

Html code:

<script>
    $('.greadingButton').on('click', function () {
        $('.greadingButton').removeClass('selected');
        $(this).addClass('selected');
    });
</script>