Add, delete and move javascript lists

JavaScript is a programming language widely used in web development. Lists are a very common element in web design. Through JavaScript, we can easily add, delete and move list elements to improve web page user experience. Next, we will discuss methods of adding, deleting, and moving lists.

1. Addition of list:

When we need to add list elements, we can do it through the following code:

// 找到要添加新列表项的父元素
var list = document.getElementById("list");
// 创建新的列表项
var newItem = document.createElement("li");
// 给新的列表项添加内容
var text = document.createTextNode("新的列表项");
newItem.appendChild(text);
// 将新的列表项添加到列表中
list.appendChild(newItem);

In the above code, we first use document.getElementById() method obtains the parent element of the new list item to be added. Then, create a new list item through the document.createElement() method, add content to the list item, and finally add the new list item to the list through the appendChild() method.

2. List deletion:

When we need to delete list elements, we can do it through the following code:

// 找到要删除的列表项
var item = document.getElementById("deleteItem");
// 找到列表项的父元素
var list = item.parentNode;
// 删除列表项
list.removeChild(item);

In the above code, we first passdocument.getElementById() method obtains the list item to be deleted. Then, get the parent element of the list item through the parentNode attribute. Finally, the list item is removed from the list through the removeChild() method.

3. List movement:

When we need to move list elements, we can use the following two methods:

1. insertBefore()Method:

This method inserts an element before the specified element. Moving list elements can be achieved through the following code:

// 找到要移动的列表项
var item = document.getElementById("moveItem");
// 找到要插入到的位置
var location = document.getElementById("beforeLocation");
// 找到列表项的父元素
var list = item.parentNode;
// 移动列表项到指定位置之前
list.insertBefore(item, location);

In the above code, we first obtain the list item to be moved and the position to be inserted through the document.getElementById() method. Then, get the parent element of the list item through the parentNode attribute. Finally, the list item is inserted before the specified position through the insertBefore() method.

2. appendChild() Method:

This method inserts a new element at the end of the child element list of the specified element. Moving list elements can be achieved through the following code:

// 找到要移动的列表项
var item = document.getElementById("moveItem");
// 找到要移动到的位置
var location = document.getElementById("afterLocation");
// 找到列表项的父元素
var list = item.parentNode;
// 从列表中删除该列表项
list.removeChild(item);
// 将该列表项添加到新的位置
location.appendChild(item);

In the above code, we first obtain the list item to be moved and the position to be moved to through the document.getElementById() method. Then, get the parent element of the list item through the parentNode attribute. Then, use the removeChild() method to remove the list item from the original list. Finally, use the appendChild() method to add the list item to the new location.

Summary:

JavaScript provides a variety of methods to add, delete and move list elements. Developers can choose appropriate methods based on specific needs to improve web page user experience.

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