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javascript set border

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Release： 2023-05-16 10:43:07

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JavaScript is a powerful and flexible programming language that can be used to create interactive websites and add more functions and creativity to the website. In this article, we will learn how to style the borders of website elements using JavaScript.

Setting the border style is one of the most common ways to change the appearance of a web page. This function can be achieved well using CSS styles, but sometimes we need to set borders on dynamically generated web page elements, and then we need to use JavaScript.

There are two main ways to set the border style of an element in JavaScript: using the style attribute and using classList.

Use the style attribute to set the border

In JavaScript, it is a very common method to use the style attribute to manipulate the style of an element. We can change the style of an element by setting the style attribute on the element and assigning a value.

As shown below, we will create a simple HTML document containing a button. When the user clicks the button, we will use JavaScript to set the button's border color and width.

<!DOCTYPE html>
<html>
<head>
    <title>JavaScript设置边框</title>
    <style>
        button {
            padding: 20px;
            font-size: 20px;
            background-color: navy;
            color: white;
            border: none;
        }
    </style>
</head>
<body>
    <button onclick="setBorder()">设置边框</button>
    <script>
        function setBorder() {
            var button = document.getElementsByTagName("button")[0];
            button.style.border = "5px solid yellow";
        }
    </script>
</body>
</html>

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In the above code, we define a button element in the HTML document. When the user clicks the button, we use JavaScript to get the element and set the color and width of its border. In the setBorder function, we use the document.getElementsByTagName method to get the button element in the page, and use the style attribute to set the border style.

Use classList to set the border

classList is a very practical attribute in JavaScript, which allows us to easily add, remove and switch the class of an element. By adding classes, we can set various styles of elements, including border styles.

As shown below, we will once again create an HTML document containing two buttons. When the user clicks the first button, we will add a class to the second button using JavaScript. This class will set the button's border style.

<!DOCTYPE html>
<html>
<head>
    <title>JavaScript设置边框</title>
    <style>
        button {
            padding: 20px;
            font-size: 20px;
            background-color: navy;
            color: white;
            border: none;
        }
        .border {
            border: 5px solid yellow;
        }
    </style>
</head>
<body>
    <button onclick="addBorder()">添加边框</button>
    <button onclick="resetBorder()">重置边框</button>
    <script>
        function addBorder() {
            var button = document.getElementsByTagName("button")[1];
            button.classList.add("border");
        }
        function resetBorder() {
            var button = document.getElementsByTagName("button")[1];
            button.classList.remove("border");
        }
    </script>
</body>
</html>

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In the above code, we define two button elements. When the user clicks the first button, we add a border class to the second button using classList. This border class is defined in the CSS style and has a yellow 5-pixel border. When the user clicks the second button, we use the classList method to remove the border class from the second button, thus resetting the border style.

Summary

Setting the border style of web page elements in JavaScript is a very common requirement. By using the style attribute or classList method, we can easily implement this function to add more creativity and functionality to the web page. Although the above examples are relatively simple, these methods can be applied to various situations, allowing you to easily master more skills in web design.

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