Are Quotes Required When Using the `url()` Function in CSS?

Is Quoting Url() Values Optional?

The use of quotes in the value of url() is a common dilemma in CSS. Let's delve into the W3C specifications to determine the recommended approach.

W3C Specifications

According to the W3C syntax for url(), quotes are not mandatory. The following three ways are all considered valid:

background-image: url(image.png);
background-image: url("image.png");
background-image: url('image.png');

Therefore, it's optional to use quotes in url() values. However, there are certain considerations to keep in mind.

Identical Opening and Closing Quotes

If quotes are used, it's important to ensure that the opening and closing quotes are the same character. For example, using a single quote for the opening quote and a double quote for the closing quote is not allowed.

Special Characters in URLs

If the URL contains special characters, such as parentheses or whitespace, it's recommended to use quotes or escape the characters. Escaping involves using a backslash before the special character. For instance:

background-image: url("image/\(x\).png");
background-image: url(image/\(x\).png);

Conclusion

In summary, quoting url() values is optional but can be beneficial in certain situations. It's essential to use identical opening and closing quotes and to account for special characters if necessary. By following these guidelines, you can ensure that your CSS code is both valid and robust.

The above is the detailed content of Are Quotes Required When Using the `url()` Function in CSS?. For more information, please follow other related articles on the PHP Chinese website!