Can you please explain the function of this JavaScript code for the Isotope filter?

Question

Can you please explain the function of this JavaScript code for the Isotope filter?

I am struggling to grasp the functionality of a section of vanilla JS code related to the Isotope filter. You can find the original code here.

var buttonGroups = document.querySelectorAll('.button-group');

for (var i = 0; i < buttonGroups.length; i++) {
  var buttonGroup = buttonGroups[i];
  var onButtonGroupClick = getOnButtonGroupClick(buttonGroup);
  buttonGroup.addEventListener('click', onButtonGroupClick);
}

function getOnButtonGroupClick(buttonGroup) {
  return function(event) {
    // check for only button clicks
    var isButton = event.target.classList.contains('button');
    if (!isButton) {
      return;
    }
    var checkedButton = buttonGroup.querySelector('.is-checked');
    checkedButton.classList.remove('is-checked')
    event.target.classList.add('is-checked');
  }
}

Can someone explain the relationship between the getOnButtonGroupClick function and its assignment to a variable in the preceding for loop?

javascript

Answer 1

Answer №1

getButtonGroupClick creates a closure that stores the value of buttonGroup. This closure is used when a button in the group is clicked - it searches for the currently selected button, deselects it, and selects the newly clicked button.

In reality, this level of complexity is unnecessary. When an event listener is triggered, event.currentTarget refers to the element the listener is attached to, simplifying the process.

var buttonGroups = document.querySelectorAll('.button-group');

for (var i = 0; i < buttonGroups.length; i++) {
  var buttonGroup = buttonGroups[i];
  buttonGroup.addEventListener('click', onButtonGroupClick);
}

function OnButtonGroupClick(event) {
  // only handle button clicks
  var isButton = event.target.classList.contains('button');
  if (!isButton) {
    return;
  }
  var checkedButton = event.currentTarget.querySelector('.is-checked');
  checkedButton.classList.remove('is-checked')
  event.target.classList.add('is-checked');
}

Answer 2

getButtonGroupClick creates a closure that stores the value of buttonGroup. This closure is used when a button in the group is clicked - it searches for the currently selected button, deselects it, and selects the newly clicked button.

In reality, this level of complexity is unnecessary. When an event listener is triggered, event.currentTarget refers to the element the listener is attached to, simplifying the process.

var buttonGroups = document.querySelectorAll('.button-group');

for (var i = 0; i < buttonGroups.length; i++) {
  var buttonGroup = buttonGroups[i];
  buttonGroup.addEventListener('click', onButtonGroupClick);
}

function OnButtonGroupClick(event) {
  // only handle button clicks
  var isButton = event.target.classList.contains('button');
  if (!isButton) {
    return;
  }
  var checkedButton = event.currentTarget.querySelector('.is-checked');
  checkedButton.classList.remove('is-checked')
  event.target.classList.add('is-checked');
}

Answer 3

Answer №2

The purpose of the for loop in this code is to iterate through all elements with the class of button-group and attach a click event listener to each of them. The function getOnButtonGroupClick generates a function that will act as the event listener for when an element is clicked.

var buttonGroups = document.querySelectorAll('.button-group');
//Select all elements with the class name 'button-group' from the document
//Stored in the NodeList variable 'buttonGroups'

for (var i = 0; i < buttonGroups.length; i++) {
//Loop through each element with the 'button-group' class
  var buttonGroup = buttonGroups[i];
  //Get the specific element at index i
  var onButtonGroupClick = getOnButtonGroupClick(buttonGroup);
  //Generate the function to be executed when the element is clicked
  buttonGroup.addEventListener('click', onButtonGroupClick);
  //Assign the generated function as the click event listener for the element
}

function getOnButtonGroupClick(buttonGroup) {
  return function(event) {
    // Check if the click event occurred on a button
    var isButton = event.target.classList.contains('button');
    //Verify if the clicked element has the class 'button'
    if (!isButton) {
      //Do nothing if the clicked element is not a button
      return;
    }
    var checkedButton = buttonGroup.querySelector('.is-checked');
    checkedButton.classList.remove('is-checked')
    event.target.classList.add('is-checked');
  }
}

Answer 4

The purpose of the for loop in this code is to iterate through all elements with the class of button-group and attach a click event listener to each of them. The function getOnButtonGroupClick generates a function that will act as the event listener for when an element is clicked.

var buttonGroups = document.querySelectorAll('.button-group');
//Select all elements with the class name 'button-group' from the document
//Stored in the NodeList variable 'buttonGroups'

for (var i = 0; i < buttonGroups.length; i++) {
//Loop through each element with the 'button-group' class
  var buttonGroup = buttonGroups[i];
  //Get the specific element at index i
  var onButtonGroupClick = getOnButtonGroupClick(buttonGroup);
  //Generate the function to be executed when the element is clicked
  buttonGroup.addEventListener('click', onButtonGroupClick);
  //Assign the generated function as the click event listener for the element
}

function getOnButtonGroupClick(buttonGroup) {
  return function(event) {
    // Check if the click event occurred on a button
    var isButton = event.target.classList.contains('button');
    //Verify if the clicked element has the class 'button'
    if (!isButton) {
      //Do nothing if the clicked element is not a button
      return;
    }
    var checkedButton = buttonGroup.querySelector('.is-checked');
    checkedButton.classList.remove('is-checked')
    event.target.classList.add('is-checked');
  }
}

Answer 5

Answer №3

If I have interpreted your query correctly, it appears that a click event is being attached to each button within the buttonGroups. In my opinion, a more efficient and organized approach would be to utilize a forEach loop, as demonstrated below:

const buttonGroups = document.querySelectorAll('.button-group');
buttonGroups.forEach(button => button.addEventListener("click", handleClick)

function handleClick(event) {
  // checking for button clicks only
  let isButton = event.target.classList.contains('button');
  if (!isButton) {
    return;
  }
  let checkedButton = event.currentTarget.querySelector('.is-checked');
  checkedButton.classList.remove('is-checked')
  event.target.classList.add('is-checked');
}

Essentially, you are associating a click event with every button within the buttonGroups, triggering the function handleClick.

UPDATE: There is no real necessity to assign the function in that manner... instead, simply invoke it during the click event.

Answer 6

If I have interpreted your query correctly, it appears that a click event is being attached to each button within the buttonGroups. In my opinion, a more efficient and organized approach would be to utilize a forEach loop, as demonstrated below:

const buttonGroups = document.querySelectorAll('.button-group');
buttonGroups.forEach(button => button.addEventListener("click", handleClick)

function handleClick(event) {
  // checking for button clicks only
  let isButton = event.target.classList.contains('button');
  if (!isButton) {
    return;
  }
  let checkedButton = event.currentTarget.querySelector('.is-checked');
  checkedButton.classList.remove('is-checked')
  event.target.classList.add('is-checked');
}

Essentially, you are associating a click event with every button within the buttonGroups, triggering the function handleClick.

UPDATE: There is no real necessity to assign the function in that manner... instead, simply invoke it during the click event.

Can you please explain the function of this JavaScript code for the Isotope filter?

Answer №1

Answer №2

Answer №3

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