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How to replace HTML content using JavaScript

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Release： 2023-04-25 15:22:01

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JavaScript is a scripting language widely used in web development, and it can play many roles on the web client. In many implementations, JavaScript is commonly used to dynamically create web content, which includes replacing HTML text content. In this article, we will focus on how to replace HTML content using JavaScript.

HTML Replacement Overview

Replacement HTML elements can make web pages more dynamic by using JavaScript to conditionally change HTML content without having to reload the page. This is very useful because it can automatically update web page content when users interact with the page, making the web page more responsive and giving users a better experience.

HTML Replacement API

To understand the replacement of HTML elements, we first need to understand the DOM (Document Object Model) and the built-in JavaScript API. DOM is the object representation of an HTML document. It describes the hierarchical structure of HTML elements and how to access HTML elements using JavaScript, and defines a series of APIs to manipulate HTML elements through JavaScript.

The APIs for replacing HTML in JavaScript mainly include the following:

1. getElementById()：此方法用来获取指定 id 的 DOM 元素。
2. getElementsByTagName()：此方法用于根据元素名称获取元素列表。
3. innerHTML：此属性用于获取或设置 DOM 元素的 HTML 内容。
4. outerHTML：此属性用于获取或设置 DOM 元素及其所有子元素的完整 HTML 内容。

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Through these APIs, HTML content can be easily replaced.

How to implement HTML content replacement

Below we will introduce how to use the above API to implement HTML content replacement.

getElementById method

To replace the content of a single element, you can use the getElementById method to obtain a reference to the element. This method will return the DOM element with the specified id.

<!DOCTYPE html>
<html>
 <body>

  <h1 id="myHeading">Hello World!</h1>

  <button onclick="replaceHeading()">Click me</button>

  <script>
   function replaceHeading() {
    var element = document.getElementById("myHeading");
    element.innerHTML = "Have a nice day!";
  }
  </script>

 </body>
</html>

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The above code demonstrates how to use the getElementById method to replace the content of the element with the id "myHeading". We call the replaceHeading() function on a button click, which uses the innerHTML property to set the content of the element to "Have a nice day!" After running the code, clicking the button will change the content of the h1 element.

getElementsByTagName method

If you do not know the id of the element you want to replace, you can use the getElementsByTagName method to get a list of HTML elements by this name. In this case, you can select the specific element you want to replace and then replace its content with the desired content. Take a look at the example below:

<!DOCTYPE html>
<html>
 <body>

  <h1>Hello World!</h1>
  <h2>Have a nice day!</h2>

  <button onclick="replaceHeading()">Click me</button>

  <script>
   function replaceHeading() {
    var elements = document.getElementsByTagName("h2");
    elements[0].innerHTML = "It is a beautiful day!";
  }
  </script>

 </body>
</html>

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In this example, we have two headings, one is h1 and the other is h2. When we click the button, the replaceHeading function will change the text in the h2 element, replacing it with "It's a great day!". Note that we used the getElementsByTagName method to get the h2 element and then changed its innerHTML property.

outerHTML attribute

If you need to completely replace an element and all its child elements, you can use the outerHTML attribute. This property returns the HTML content of the element and all its child elements. You can change the outerHTML attribute to replace the entire element and its content. For example:

<!DOCTYPE html>
<html>
 <body>

  <div id="myDiv">
   <h1>Hello World!</h1>
   <p>Welcome to JavaScript.</p>
  </div>

  <button onclick="replaceDiv()">Click me</button>

  <script>
    function replaceDiv() {
      var oldDiv = document.getElementById("myDiv");
      var newDiv = document.createElement("div");
      newDiv.innerHTML = "<h3>Welcome to the New World!</h3>";
      oldDiv.outerHTML = newDiv.outerHTML;
    }
  </script>

 </body>
</html>

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In this example, we first define a div element that contains the title and paragraph. We then create a new div element, set its innerHTML property to the new title, and then set its outerHTML property to the old div element's outerHTML property. This will replace the entire div element and its content.

Summary

In this article, we discussed the importance of JavaScript in replacing HTML content in web development and introduced some JavaScript APIs for manipulating HTML elements. We showed you an example of using the getElementById, getElementsByTagName and outerHTML methods as well as the innerHTML property to replace an HTML element and its content. Using these methods is ideal if you need to bring more dynamics and interactivity to your web pages.

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