What is the syntax of finding elements by id using CSS Selector?

In CSS Selector, the hash (#) notation selects elements by their id attribute.

Syntax:

#idValue
tagName#idValue

Java examples:

driver.findElement(By.cssSelector("#username"));
driver.findElement(By.cssSelector("input#username"));
driver.findElement(By.cssSelector("#loginForm .submit-btn"));
driver.findElement(By.cssSelector("#container input[type=''text'']"));

Comparison:

Best Practice: For elements with unique IDs, By.id() is fastest. Use CSS #id when you need to combine with other selectors like #form input[type=''text''].