Explore how JavaScript can directly modify web pages

1. Foreword

In the process of Web development, JavaScript is one of the most commonly used languages. One of the most important uses is to operate web page elements and achieve interactive effects. One of the ways to achieve the above operations is to directly modify the web page. In this article, we will explore how JavaScript can directly modify web pages.

2. Three ways to directly modify web pages

2.1. innerHTML

innerHTML is one of the most commonly used methods to directly modify web pages. It can directly change elements. HTML content, for example:

document.getElementById("demo").innerHTML = "Hello world!";

The above code will change the HTML content of an element with the id "demo" to "Hello world!".

2.2. style

The style attribute can change the CSS style of the element, including but not limited to background color, font color, font size, etc., for example:

document.getElementById("demo").style.color = "red";

The above code The text color of an element with the id "demo" will be changed to red.

2.3. attribute

The attribute attribute can change the attributes of the element, for example:

document.getElementById("demo").src = "new-image.jpg";

The above code will change the image address of an element with the id "demo".

3. How to apply

How to apply the above three methods of directly modifying web pages? The following is a basic application example:

    



直接修改网页元素

Hello World

点击这里更改元素内容

<script>
function changeContent() {
    document.getElementById("demo").innerHTML = "Hello JavaScript!";
    document.getElementById(&quot;demo&quot;).style.color = &quot;red&quot;;
    document.getElementById("demo").style.fontSize = "22px";
    document.getElementById(&quot;demo&quot;).src = &quot;new-image.jpg&quot;;
}
</script>

The above code defines an element with the id "demo", and after clicking the button, the HTML content, text color, and text color of the element are changed by calling the function changeContent(). Font size and image address.

4. Precautions

It is worth noting that in the process of directly modifying the web page, we should pay attention to page performance and security issues. If you perform frequent operations on web page elements, it will occupy a lot of CPU and memory, which may cause the page to freeze or crash. At the same time, when it comes to user input operations, we should pay attention to preventing XSS attacks and ensure the security of the page by fully filtering and verifying user input.

5. Summary

Directly modifying web page elements with JavaScript is one of the most common operations in web development. We can achieve this through innerHTML, style and attribute. However, we should pay attention to page performance and security issues during operation, and improve code quality and maintainability to ensure a good experience of page interaction effects.

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