Can not delete an element of array in JavaScript

Question

I have a part of code in which the function removeClass must delete an element of array in case, if some of his elements coincides with input parameters.

But it does not work.

var obj = {
  className: 'open menu'
};

function removeClass(obj, cls) {
  var arr = obj.className.split(' ');

  for (var i = 0; i < arr.Length; i++) {
    if (cls == arr[i]) delete arr[i]
  }

  obj.className = arr.join(' ');

  return obj.className;
}

console.log(removeClass(obj, 'open'));
// desired output obj.className='menu'
// actual output 'open menu'

What doesn't work? You haven't provided any errors, or output or anything to give us any clear indication to what your problem is. — CodeLikeBeaker
– CodeLikeBeaker, Commented Dec 13, 2017 at 16:43
Are you trying to be able to remove values from the className of a DOM element? If so there are easier ways to do this. — Intervalia
– Intervalia, Commented Dec 13, 2017 at 16:44

Vipin Kumar · Accepted Answer · 2017-12-13 16:56:01Z

3

You can use Array.prototype.filter() method for this.

var obj = {
  className: 'open menu'
};

function removeClass(obj, cls) {
  var arr = obj.className.split(' ');

  obj.className = arr.filter(function(item) {
    return cls !== item;
  }).join(' ')

  return obj.className;
}

console.log(removeClass(obj, 'open'));

In your code, you have used arr.Length. Actual syntax is arr.length. But even if you use fix your code then, it will not delete the item instead put undefined on its place, then you have to handle extra white spaces. That's why I think above solution is good.

edited Dec 13, 2017 at 16:56

answered Dec 13, 2017 at 16:49

Vipin Kumar

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Comments

Intervalia · Accepted Answer · 2017-12-13 17:08:22Z

1

Try this:

    var obj = {
      className: 'open menu dogs cats'
    };

    function removeClass(obj, cls) {
      return (obj.className = obj.className.split(' ').filter(item => cls !== item).join(' '));
    }

    console.log(removeClass(obj, 'open'));
    console.log(removeClass(obj, 'dogs'));

But if you are trying to do this to a DOM element then use classList instead.

var el = document.getElementById("mine");

console.log(el.className);
el.classList.remove('open');
console.log(el.className);
el.classList.remove('dogs');
console.log(el.className);

<div id="mine" class="menu open dogs cats"></div>

edited Dec 13, 2017 at 17:08

answered Dec 13, 2017 at 16:49

Intervalia

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Comments

Maciej Kozieja · Accepted Answer · 2017-12-13 16:53:15Z

0

Why just don't replace the string?

var obj = {
  className: 'open menu'
};

function removeClass(obj, cls) {
  return obj.className = obj.className.replace(cls, '').trim()
}

console.log(removeClass(obj, 'open')); // obj.className='menu'

Also while working with DOM there are already methods for dooing this

const b = document.querySelector('button')
b.addEventListener('click', () => {
  b.classList.remove('blue')
})

.red {
  color: red
}

.blue {
  color: blue
}

<button class="red blue">test</button>

answered Dec 13, 2017 at 16:53

Maciej Kozieja

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Comments

Rogier Slag · Accepted Answer · 2017-12-13 16:55:10Z

0

With ES6 you can even make this really short

function removeClass(element, classToRemove) {
    return element.className.split(' ')
                  .filter(class => class !== classToRemove)
                  .join(' ');
}

If you want to modify the element itself, just reassign the return value to element.className

answered Dec 13, 2017 at 16:55

Rogier Slag

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