Javascript - How to add event delegation to "change" event (not click) on radio buttons?

meowalarm
September 7, 2024
58 views
0 votes
2 Answers

I often times easily implemented event delegation with the "click" event on parent elements of something with code like

HTML:

<div>
  <span>
    <input
      type="radio"
      id="all0"
      name="difficulty-ask"
      class="difficultyaskclass"
      value="all"
      checked="checked"
    />
    <label for="all0">All</label>
    <input
      type="radio"
      id="2easy1"
      name="difficulty-ask"
      class="difficultyaskclass"
      value="easy"
    />
    <label for="2easy1">Easy</label>
    <input
      type="radio"
      id="2med2"
      name="difficulty-ask"
      class="difficultyaskclass"
      value="medium"
    />
    <label for="2med2">Medium</label>
    <input
      type="radio"
      id="2hard3"
      name="difficulty-ask"
      class="difficultyaskclass"
      value="hard"
    />
    <label for="2hard3">Hard</label>
  </span>
</div>

JS:

parentelement.addEventlistener('click', (event) => {
if(event.target.classList.contains('targetelement'){Code..}};

(parentelement is just a regular div, in which the radio buttons are placed)

How does it work now with the ‘change’ event for example for radio buttons if they switch state?

I made it work first by just looping through all of them and then add an eventListener to each. But this is obviously not the desired solution, i definitely need some event delegation there.

Answers

you may use input event, which is also valid for any forms elements

demo:

const myForm = document.forms['my-form'];
  
myForm.addEventListener('submit', e => 
  {
  e.preventDefault(); // disable submit - page reload
  const formValues = Object.fromEntries(new FormData(myForm).entries());
  console.log( formValues );
  setInterval(console.clear,8000);
  })

myForm.addEventListener('input', e => 
  {
  if (!e.target.matches('input[type="radio"]')) return;
  
  console.log(myForm['difficulty-ask'].value);
  setInterval(console.clear,2000);
  });

label    { display: block; cursor: pointer; }
fieldset { width: fit-content; }

<form name="my-form">
  <fieldset>
    <legend> difficulty </legend>
    <label>
      <input name="difficulty-ask" type="radio" value="all" checked >
      All
    </label>
    <label>
      <input name="difficulty-ask" type="radio" value="easy" >
      Easy
    </label>
    <label>
      <input name="difficulty-ask" type="radio" value="medium" >
      Medium
    </label>
    <label>
      <input name="difficulty-ask" type="radio" value="hard" >
      Hard
    </label>
  </fieldset>
  <button>submit</button>
</form>

You can also use click or also change as you have2 choice value. You can use event delegation combined with call() method. here I added event delegation to an added input type checkbox

const div = document.querySelector('div')
console.log(div)
div.addEventListener('change',(e)=>{
    let target = e.target
    if(target.matches("input[type='checkbox']")){
        check.call(e.target,e)
    }
})


function check(){
    console.log(this.value)
}

    <div>
        <span>
          <input
            type="radio"
            id="all0"
            name="difficulty-ask"
            class="difficultyaskclass"
            value="all"
            checked="checked"
          />
          <label for="all0">All</label>
          <input
            type="radio"
            id="2easy1"
            name="difficulty-ask"
            class="difficultyaskclass"
            value="easy"
          />
          <label for="2easy1">Easy</label>
          <input
            type="radio"
            id="2med2"
            name="difficulty-ask"
            class="difficultyaskclass"
            value="medium"
          />
          <label for="2med2">Medium</label>
          <input
            type="radio"
            id="2hard3"
            name="difficulty-ask"
            class="difficultyaskclass"
            value="hard"
          />
          <label for="2hard3">Hard</label>
          <label for="2med45">checkbox</label>
          <input
            type="checkbox"
            id="2hard36"
            name="difficulty-ask1"
            class="difficultyaskclass5"
            value="hardtoveryhard"
          />
          <label for="2hard36">Hard</label>
        </span>
      </div>

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Javascript – How to add event delegation to "change" event (not click) on radio buttons?

Answers