javascript select modify

JavaScript is a programming language widely used in web development. It can achieve dynamic effects on web pages by selecting DOM elements and modifying them. This article covers selection and modification in JavaScript.

Selection

JavaScript can select DOM elements in the following ways:

1. Tag name selector

Use the tag name selector to select all elements in the web page The element with this tag name. For example, to select all p elements:

var pElements = document.getElementsByTagName("p");

2. ID selector

Use the ID selector to select elements with a specific ID. For example, select the element with the ID "myDiv":

var myDiv = document.getElementById("myDiv");

3. class selector

Use the class selector to select elements with a specific class name. For example, select elements with class "myClass":

var myElements = document.getElementsByClassName("myClass");

4. Attribute selector

Use the attribute selector to select elements with specific attributes. For example, to select all elements with the "data-type" attribute:

var elementsWithType = document.querySelectorAll("[data-type]");

Modify

With the select element method, JavaScript can also modify the selected element.

1. Modify the text content of the element

You can change the text content of the element by modifying the innerHTML attribute of the element. For example, change the text content of the element with the ID "myDiv" to "Hello World!":

var myDiv = document.getElementById("myDiv");
myDiv.innerHTML = "Hello World!";

2. Modify the style of the element

You can change the style of the element by modifying the style attribute of the element. CSS styles. For example, change the background color of the element with the ID "myDiv" to red:

var myDiv = document.getElementById("myDiv");
myDiv.style.backgroundColor = "red";

3. Modify the class of the element

You can change the class of the element by modifying the className attribute of the element. For example, change the class of the element with the ID "myDiv" to "newClass":

var myDiv = document.getElementById("myDiv");
myDiv.className = "newClass";

4. Modify the attributes of the element

You can change other attributes of the element by modifying the attributes of the element. For example, change the alt attribute of the element with the ID "myDiv" to "newAlt":

var myDiv = document.getElementById("myDiv");
myDiv.alt = "newAlt";

Conclusion

JavaScript can achieve dynamic effects on web pages by selecting DOM elements and modifying them. This article introduces selection and modification in JavaScript, including tag name selectors, ID selectors, class selectors, attribute selectors, and modifying the text content, style, class, and attributes of elements. Mastering these skills allows developers to use JavaScript more flexibly in website development.

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