如何通过父元素查找孙元素？定位范围及正确方法咨询

Hey there! Let's tackle your three questions step by step, with clear explanations and examples:

1. Can A.element(by.css(.c)) get a <div> with class c? #

It can, but first fix the syntax: you need to wrap the CSS selector in quotes and ensure the class selector is properly formatted. The correct code should be:

A.element(by.css('.c'))

This will locate the first element with class c that exists within the subtree of element A (including direct children, grandchildren, and deeper descendants). As long as your target <div> has the c class and is inside A, this locator will find it.

2. Does ParentElement.element(locator) only find direct children, or does it include grandchildren? #

Great question! ParentElement.element(locator) searches the entire subtree of ParentElement—meaning it will match any descendant element, not just direct children. This includes grandchildren, great-grandchildren, and so on.

If you specifically wanted only direct children, you'd need to use a locator that targets direct descendants, like:

• CSS: by.css(':scope > .target-class') (the > symbol selects direct children, :scope refers to ParentElement itself)
• XPath: by.xpath('./child::*[@class="target-class"]')

3. What's the correct way to find a grandchild element of the parent? #

As mentioned earlier, ParentElement.element(by.css('.c')) already works for finding grandchildren (since it searches all descendants). But if you need to explicitly target only grandchildren (and skip direct children), you can use more precise locators:

Option 1: CSS Selector #

Use the direct child combinator (>) twice to target elements two levels deep:

ParentElement.element(by.css(':scope > * > .c'))

• :scope = ParentElement
• > * = Any direct child of ParentElement
• > .c = Any direct child of that element (i.e., the grandchild of ParentElement)

If you know the tag name of the intermediate child, you can make it more specific:

ParentElement.element(by.css(':scope > div > .c'))

Option 2: XPath #

Use the child:: axis twice to target grandchildren:

ParentElement.element(by.xpath('./child::*/child::*[@class="c"]'))

Or if you know the intermediate tag:

ParentElement.element(by.xpath('./child::div/child::div[@class="c"]'))

Example HTML for Context #

Let's say you have this structure:

<div class="parent">
  <div class="direct-child">Direct child content</div>
  <div class="middle-child">
    <div class="c">Target grandchild</div>
  </div>
</div>

• ParentElement.element(by.css('.c')) will find the <div class="c"> (grandchild)
• ParentElement.element(by.css(':scope > .c')) would not find anything (since there's no direct child with class c)
• ParentElement.element(by.css(':scope > .middle-child > .c')) explicitly targets the grandchild inside .middle-child

内容的提问来源于stack exchange，提问作者Golden Heart