JavasScript Siblings (ok)

https://www.javascripttutorial.net/javascript-dom/javascript-siblings/

Fujifilm/gbalb-demo.cybozu.com4913/live.html

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>JavaScript Siblings</title>
</head>
<body>
  <ul id="menu">
    <li>Home</li>
    <li>Products</li>
    <li class="current">Customer Support</li>
    <li>Careers</li>
    <li>Investors</li>
    <li>News</li>
    <li>About Us</li>
  </ul>
  <script>
  let getSiblings = function(e) {
    // for collecting siblings
    let siblings = [];
    // if no parent, return no sibling
    if (!e.parentNode) {
      return siblings;
    }
    // first child of the parent node
    let sibling = e.parentNode.firstChild;
    // collecting siblings
    while (sibling) {
      if (sibling.nodeType === 1 && sibling !== e) {
        siblings.push(sibling);
      }
      sibling = sibling.nextSibling;
    }
    return siblings;
  };
  let siblings = getSiblings(document.querySelector('.current'));
  siblingText = siblings.map(e => e.innerHTML);
  console.log(siblingText);
  </script>
</body>
</html>

JavasScript Siblings

Summary: in this tutorial, you will learn how to select the next siblings, previous siblings, and all siblings of an element. Let’s say you have the following list of items:

<ul id="menu">
    <li>Home</li>
    <li>Products</li>
    <li class="current">Customer Support</li>
    <li>Careers</li>
    <li>Investors</li>
    <li>News</li>
    <li>About Us</li>
</ul>
Code language: HTML, XML (xml)

Get the next siblings

To get the next sibling of an element, you use the nextElementSibling attribute:

let nextSibling = currentNode.nextElementSibling;Code language: JavaScript (javascript)

The nextElementSibling returns null if the specified element is the first one in the list. The following example uses the nextElementSibling property to get the next sibling of the list item that has the current class:

let current = document.querySelector('.current');
let nextSibling = current.nextElementSibling;
console.log(nextSibling);Code language: JavaScript (javascript)

Output:

<li>Careers</li>
Code language: HTML, XML (xml)

In this example:

First, select the list item whose class is current using the querySelector().
Second, get the next sibling of that list item using the nextElementSibling property.

To get all the next siblings of an element, you can use the following code:

let current = document.querySelector('.current');
let nextSibling = current.nextElementSibling;

while(nextSibling) {
    console.log(nextSibling);
    nextSibling = nextSibling.nextElementSibling;
}Code language: JavaScript (javascript)

Get the previous siblings

To get the previous siblings of an element, you use the previousElementSibling attribute:

let current = document.querySelector('.current');
let prevSibling = currentNode.previousElementSibling;Code language: JavaScript (javascript)

The previousElementSibling property returns null if the current element is the first one in the list.

The following example uses the previousElementSibling property to get the previous siblings of the list item that has the current class:

let current = document.querySelector('.current');
let prevSiblings = current.previousElementSibling;
console.log(prevSiblings);
Code language: JavaScript (javascript)

And the following example selects all the previous siblings of the list item that has the current class:

let current = document.querySelector('.current');
let prevSibling = current.previousElementSibling;
while(prevSibling) {
    console.log(prevSibling);
    prevSibling = current.previousElementSibling;
}
Code language: JavaScript (javascript)

Get all siblings of an element

To get all siblings of an element, we’ll use the logic:

First, select the parent of the element whose siblings that you want to find.
Second, select the first child element of that parent element.
Third, add the first element to an array of siblings.
Fourth, select the next sibling of the first element.
Finally, repeat the 3rd and 4th steps until there are no siblings left. In case the sibling is the original element, skip the 3rd step.

The following function illustrates the steps:

let getSiblings = function (e) {
    // for collecting siblings
    let siblings = []; 
    // if no parent, return no sibling
    if(!e.parentNode) {
        return siblings;
    }
    // first child of the parent node
    let sibling  = e.parentNode.firstChild;
    
    // collecting siblings
    while (sibling) {
        if (sibling.nodeType === 1 && sibling !== e) {
            siblings.push(sibling);
        }
        sibling = sibling.nextSibling;
    }
    return siblings;
};
Code language: JavaScript (javascript)

Put it all together:

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>JavaScript Siblings</title>
</head>
<body>
    <ul id="menu">
        <li>Home</li>
        <li>Products</li>
        <li class="current">Customer Support</li>
        <li>Careers</li>
        <li>Investors</li>
        <li>News</li>
        <li>About Us</li>
    </ul>
    
    <script>
        let getSiblings = function (e) {
            // for collecting siblings
            let siblings = []; 
            // if no parent, return no sibling
            if(!e.parentNode) {
                return siblings;
            }
            // first child of the parent node
            let sibling  = e.parentNode.firstChild;
            // collecting siblings
            while (sibling) {
                if (sibling.nodeType === 1 && sibling !== e) {
                    siblings.push(sibling);
                }
                sibling = sibling.nextSibling;
            }
            return siblings;
        };

        let siblings = getSiblings(document.querySelector('.current'));
        siblingText = siblings.map(e => e.innerHTML);
        console.log(siblingText);
    </script>
</body>
</html>
Code language: HTML, XML (xml)

Output:

["Home", "Products", "Careers", "Investors", "News", "About Us"]
Code language: JSON / JSON with Comments (json)

Summary

The nextElementSibling returns the next sibling of an element or null if the element is the last one in the list.
The previousElementSibling returns the previous sibling of an element or null if the element is the first one in the list.
To get all siblings of an element, you can use a helper function that utilizes the nextElementSibling property.

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Last updated 2 years ago