Javascript modifies element attributes

Javascript is a very popular scripting language that can help developers add various interactive effects to web pages. Among them, modifying element attributes is a common operation in Javascript. In this article, I will introduce the basic knowledge and practical application of Javascript to modify element attributes.

1. Introduction to element attributes

In HTML, each element has some attributes to describe its content or to control during user interaction. For example, common element attributes include id, class, src, href, etc. These properties can be modified through Javascript to achieve various dynamic effects.

2. Basics of Javascript modifying element attributes

1. getElementById() method

To modify the attributes of an element, you first need to select the element to be modified. The most commonly used method is to use the getElementById() method, which finds the element with the specified id in the HTML page. For example, if there is an element with the id "elementId" in HTML, you can use the following code to obtain the element:

var element = document.getElementById("elementId");

Through the above code, the variable element saves the reference to this element, and you can manipulate the variable to Modify an element's properties.

2. Attribute operation

The most basic operation to modify the attributes of an element is to modify the attributes of the element. For example, you can use the following code to change the background color of an element to red:

element.style.backgroundColor = "red";

In the above code, style represents the style attribute of the element. You can also change the background color to another color, change the text size, set borders, and more.

3. Attribute acquisition

By finding the attribute of the element and getting the value of the attribute, we can obtain the attribute information of the specified element in Javascript. For example, the class attribute of an element can be obtained through the following code:

var className = element.className;

In this way, the attribute information of various elements can be obtained and related processing can be performed in Javascript code.

3. Practical practice of modifying element attributes with Javascript

In practice, we can use Javascript to modify element attributes to achieve various interactive effects. Next, I will introduce some common practical applications.

1. Dynamicly change pictures

We can dynamically change pictures by modifying element attributes through Javascript. For example, when the user clicks a button, we can change the src attribute of the image to achieve dynamic image switching. The sample code is as follows:

<button onclick="changeImage()">Change image</button>
<img id="myImage" src="image1.jpg" alt="">

<script>
function changeImage() {
  var image = document.getElementById("myImage");
  if (image.src.match("image1")) {
    image.src = "image2.jpg";
  } else {
    image.src = "image1.jpg";
  }
}
</script>

In the above code, by changing the src attribute of the image, the effect of dynamic image switching can be achieved.

2. Achieving animation effects

By modifying element attributes, we can also achieve animation effects. For example, you can achieve a translation animation effect by modifying the position attribute of an element. The sample code is as follows:

<div id="movingDiv" style="position:absolute;">Moving DIV</div>

<script>
var div = document.getElementById("movingDiv");
var position = 0;

function move() {
  position += 1;
  div.style.left = position + "px";
  setTimeout(move, 10);
}
move();
</script>

In the above code, we achieve the translation animation effect of the DIV element by modifying the "left" attribute of the element.

4. Summary

Through the introduction of this article, we have learned the basic knowledge of Javascript to modify element attributes, including obtaining elements, modifying attributes, obtaining attributes, etc. At the same time, we also introduced the practical application of Javascript to modify element attributes, including dynamically changing pictures, achieving animation effects, etc. For Javascript developers, it is very important to master the skills of modifying element attributes.

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