Checking a checkbox and applying the style to the corresponding input value

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I'm creating a todo list in vanilla JavaScript. Right now, I'm trying to apply a style to a todo when the corresponding checkbox is checked.

toDoContainer.addEventListener("change", function(e) {
    const tgt = e.target;
    if (tgt.classList.contains("checkbox")) {
      let toDo = tgt.closest("input").classList.contains("input");
      if (toDo.value !== "") {
          toDo.style.opacity = "50%";
      }
    }
  });

As it stands, nothing is happening visibly and I'm not getting an error.

I'm using the closest() method because the checkbox and the todo are both inputs that are right next to eachother in the DOM.

Before I was using this code -

allCheckboxes.forEach(box => {
    box.addEventListener("change", () => {
        if (box.checked) {
            for (let toDo = 0; toDo < allToDos.length; toDo++) {
                if (allToDos[toDo].value) {
                    allToDos[toDo].style.textDecoration = "line-through";
                    allToDos[toDo].style.opacity = "50%";
                }
            }
        }
        else {
            console.log("cat");
            for (let toDo = 0; toDo < allToDos.length; toDo++) {
                if (allToDos[toDo].value) {
                    allToDos[toDo].style.textDecoration = "none";
                    allToDos[toDo].style.opacity = "100%";
                }
            }
        }
    })
})

I was able to apply the styles to the inputs but only when the first checkbox in the node list was checked. Checking the checkbox also applied the styles to all of the todos in the DOM, not just the corresponding one which is what I want.

Another quirk that I've just noticed is that when I look at dev tools to see if it's logging the checkboxes it shows an empty node list - [] when there are multiple checkboxes visible.

document.getElementById("add").addEventListener("click", () => {
    console.log(allCheckboxes);
});

How can I apply styling to only the corresponding todo when a checkbox is checked?

*** EDIT - https://codepen.io/harri-greeves/pen/LYLEKNj ***

html javascript
3 Answers

I'm using the closest() method because the checkbox and the todo are both inputs that are right next to each other in the DOM.

The closest method searches the element itself and then it searches the element's ancestors, moving up the dom tree.

I don't think .closest can be used to target siblings.

https://api.jquery.com/closest/

user_89783490

The problem is on line:

const allCheckboxes = toDoContainer.querySelectorAll("[type=checkbox]");

querySelector returns not living html collection. It means that it will not include dynamically added todos.

The better way is to listen parent node: todoContainer and then manipulate state.

user_167529630

add this function

function ChangeOpacity() {
let checkbox = document.getElementsByClassName("checkbox");
  let input = document.getElementsByClassName("input");
  for (let i = 0; i < checkbox.length; i++) {
   checkbox[i].addEventListener("change",()=>{
     if (checkbox[i].checked == true) {
       if (input[i].value) {
         input[i].style.opacity = "50%"
         input[i].style.textDecoration = "line-through"
       }
       else{
        input[i].style.opacity = "100%"
        input[i].style.textDecoration = "none"
       }
     } else {
      if (input[i].value) {
        input[i].style.opacity = "50%"
        input[i].style.textDecoration = "line-through"
      }
      else{
       input[i].style.opacity = "100%"
       input[i].style.textDecoration = "none"
      }
     }
   

   })
    
  }
}
ChangeOpacity()

and then call this function to the createToDo function everything should work fine and its cleaner this way

user_111203060
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