Discuss in detail the addition, deletion and modification operations of JavaScript

JavaScript is a widely used programming language, especially for web developers, it is an indispensable part. Among them, JavaScript addition, deletion, and modification operations are one of the most frequently used operations in web development. In this article, I will discuss in detail the addition, deletion and modification operations of JavaScript and their importance in web development.

Add

The operation of adding elements in JavaScript can be achieved in two ways: document operation and code operation.

Document operation refers to processing the HTML document as an object, adding, modifying and deleting elements by obtaining elements, modifying element attributes, etc. Here is an example:

// 在id为"my-div"的元素中增加一个<p>元素
var myDiv = document.getElementById("my-div");
var pEle = document.createElement("p");
myDiv.appendChild(pEle);</p>

Code operation refers to using JavaScript code directly to add elements instead of operating HTML documents. The following is an example:

// 直接使用JavaScript代码在body结构中增加一个<p>元素
var pEle = document.createElement("p");
document.body.appendChild(pEle);</p>

Whether it is a document operation or a code operation, they can all implement the function of adding new elements to the page. Adding elements can make the web page more interactive and beautiful.

Delete

In web development, deleting elements is also a very common operation. In JavaScript, there are two ways to delete elements: document operation and code operation.

Document operations are achieved by getting the element and then removing it from the parent element. The following is an example:

// 删除id为"my-div"的元素
var myDiv = document.getElementById("my-div");
myDiv.parentNode.removeChild(myDiv);

The code operation is achieved by directly calling the remove() method. Here is an example:

// 直接使用JavaScript代码将body结构中的第一个<p>元素删除
var pEle = document.querySelector("p");
pEle.remove();</p>

No matter which method is used, the function of deleting elements on the page can be easily achieved. For dynamically displayed data, deleting elements is a very critical step.

Modification

Modifying elements is another very important operation in JavaScript. In web development, there are many situations where existing elements need to be dynamically updated. In JavaScript, we can use document operations and code operations to achieve this.

Document operation is to first obtain the element to be modified, and then modify its attributes, styles, etc. The following is an example:

// 修改id为"my-div"的元素的样式
var myDiv = document.getElementById("my-div");
myDiv.style.backgroundColor = "#ccc";

The code operation is to first obtain the element to be modified, and then modify its content using methods such as innerHTML. Here is an example:

// 使用JavaScript代码来修改id为"my-div"的元素的内容
var myDiv = document.getElementById("my-div");
myDiv.innerHTML = "<p>Hello JavaScript</p>";

Using document operations and code operations to modify elements allows us to dynamically update page content to make it more colorful.

Conclusion

In this article, we discussed the addition, deletion and modification operations of JavaScript. Whether it is document operation or code operation, they can realize the functions of addition, deletion and modification. In web development, adding, deleting and modifying elements are very common operations. Through these operations, we can achieve more dynamic and interactive pages. I hope this article will be helpful to you in your work in web development.

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