js hierarchical selectors include getElementById, getElementsByTagName, getElementsByClassName, querySelector, querySelectorAll, parentNode, children, previousSibling and nextSibling, etc. Detailed introduction: 1. getElementById, use the ID attribute of the element to select, etc.
The operating system for this tutorial: Windows 10 system, DELL G3 computer.
The hierarchical selector in JavaScript can be used to select and operate elements in the DOM tree, selecting based on the hierarchical relationship of the elements. The following are common hierarchical selectors in JavaScript:
1. getElementById: Use the ID attribute of the element to select. By setting a unique ID attribute to an element, you can select it using the getElementById method. For example, `document.getElementById("myElement")` selects the element with the ID "myElement".
2. getElementsByTagName: Use the tag name of the element to select. By specifying the tag name of an element, you can use the getElementsByTagName method to select all elements with that tag name. For example, `document.getElementsByTagName("div")` selects all `
3. getElementsByClassName: Use the class name of the element to select. By specifying the class name of an element, you can use the getElementsByClassName method to select all elements with that class name. For example, `document.getElementsByClassName("red")` selects all elements with the class name "red".
4. querySelector: Use CSS selector to select. By using CSS selector syntax, you can use the querySelector method to select the first element that meets a specified condition. For example, `document.querySelector(".red")` would select the first element with the class name "red".
5. querySelectorAll: Use CSS selectors to select. Similar to the querySelector method, the querySelectorAll method selects all elements that meet the specified conditions and returns a list of elements. For example, `document.querySelectorAll("div")` selects all `
6. parentNode: The parent element of the selected element. By using the parentNode attribute, you can select the immediate parent element of an element. For example, `element.parentNode` can select the parent element of the element element.
7. children: Select the child elements of the element. By using the children attribute, you can select the direct children of an element. For example, `element.children` selects all child elements of the element element.
8. previousSibling: Select the previous sibling element of the element. By using the previousSibling attribute, you can select an element's previous sibling element. For example, `element.previousSibling` can select the previous sibling element of element element.
9. nextSibling: Select the next sibling element of the element. By using the nextSibling attribute, you can select the next sibling element of an element. For example, `element.nextSibling` can select the next sibling element of element element.
The above are common hierarchical selectors in JavaScript. They can select and operate elements in the DOM tree according to the hierarchical relationship of the elements. By rationally using these hierarchical selectors, we can accurately select and manipulate specific elements, achieve rich and diverse effects, and improve user experience and page interactivity.
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