Core points

• NodeList.js, as an alternative to DOM operation for jQuery, offers similar functionality, but is smaller (4k after compression) and takes advantage of improvements to the native browser API.

• Unlike jQuery, NodeList.js treats node arrays as single nodes, enabling cleaner code and easier NodeList object operations.

• NodeList.js contains special methods for setting and getting attributes, calling element-specific methods, and accessing nodes in NodeList, and the prevObject attribute equivalent to jQuery's owner attribute.

• NodeList.js is compatible with mainstream browsers after a specific version (Firefox 6, Safari 5.0.5, Chrome 6, IE 9, Opera 11.6), and is automatically updated to include new methods/properties added by the browser.

  p.tip { background-color: rgba(128,128,128,0.05); border-top-right-radius: 5px; border-bottom-right-radius: 5px; padding: 15px 20px; border-left: 10px solid rgba(128,128,128,0.075); }

In recent years, jQuery has become the de facto JavaScript library on the Web. It removes a lot of cross-browser inconsistencies and adds a layer of popular syntactic sugar to client scripts. One of its main pain points in abstraction processing is DOM operations, but since the advent of jQuery, native browser APIs have been significantly improved, and the concept of "you probably don't need jQuery" has become popular.

The reasons are as follows:

1. jQuery contains many features that you don't need or use (and therefore it is unnecessary to be huge).
2. jQuery takes on too many functions for too many people. Generally, smaller libraries can do some tasks better.
3. In terms of DOM operations, the browser API can now perform most of the functions of jQuery.
4. The browser API is now more synchronized, for example using addEventListener instead of attachEvent.

What is the problem?

The problem is that using native (or pure) JavaScript for DOM can be troublesome compared to jQuery. This is because you have to write more redundant code and handle the browser's useless NodeList.

First, let's take a look at MDN's definition of NodeList:

The

NodeList object is a collection of nodes, such as those returned by the Node.childNodes and document.querySelectorAll methods.

There are sometimes dynamics NodeList (which can be confusing):

In some cases, NodeList is a dynamic collection, which means changes in the DOM are reflected in the collection. For example, Node.childNodes is dynamic.

This can be a problem because you can't tell which are dynamic and which are static. Unless you remove each node from the NodeList and then check if the NodeList is empty. If empty, you have a dynamic NodeList (it's just a bad idea).

In addition, the browser does not provide any useful methods to manipulate these NodeList objects.

For example, unfortunately, it is not possible to loop through nodes using forEach

var nodes = document.querySelectorAll('div');
nodes.forEach(function(node) {
  // do something
});
// 錯誤：nodes.forEach 不是函數(shù)

Therefore, you have to do the following:

var nodes = document.querySelectorAll('div');
for(var i = 0, l = nodes.length; i < l; i++) {
  // do something with nodes[i]
}

Or even only use "hack":

[].forEach.call(document.querySelectorAll('div'), function(node) {
    // do something
});

The browser's native NodeList has only one method:

. It returns a node from NodeList via index. When we can access the node like we use an array (using item), it is completely useless: array[index]

var nodes = document.querySelectorAll('div');
nodes.item(0) === nodes[0]; // true

This is where NodeList.js comes in - making it as easy to operate a DOM using a browser native API as using jQuery, but only requires 4k compression size.

Solution

I created NodeList.js because I've been using native DOM APIs, but want to make them more concise, thus reducing a lot of redundancy when writing code (such as for loops).

NodeList.js is a wrapper for the native DOM API that allows you to manipulate arrays of nodes (i.e. my NodeList) as if it were a single node. This gives you more functionality than the browser native NodeList object.

If you think this is good, get a copy of NodeList.js from the official GitHub repository and continue reading the rest of this tutorial.

Usage:

Selecting a DOM node is simple:

// Return to my NodeList$$(selector);

This method is used in the background

. querySelectorAll(selector)

But how does it compare to jQuery?

Glad you asked this question. Let's compare native JS, jQuery, and NodeList.js.

Suppose we have three buttons:

Let's change the text of each button to "Click Me":

Native JS:

var buttons = document.querySelectorAll('button'); // 返回瀏覽器無用的 NodeList
for(var i = 0, l = buttons.length; i < l; i++) {
  buttons[i].textContent = 'Click Me';
}

jQuery:

$('button').text('Click Me');

NodeList.js:

$$('button').textContent = 'Click Me';

Here, we see that NodeList.js can effectively treat NodeList as a single node. That is, we reference a NodeList and set its

property to "Click Me". NodeList.js then performs this for each node in the NodeList. Very clever, right? textContent

If we want a method chain (similar to jQuery), we do the following, which returns a reference to NodeList:

$$('button').set('textContent', 'Click Me');

Now, let's add a click event listener to each button:

Native JS:

var buttons = document.querySelectorAll('button'); // 返回瀏覽器無用的 NodeList
for(var i = 0, l = buttons.length; i < l; i++) {
  buttons[i].addEventListener('click', function() {
    this.classList.add('clicked');
  });
}

jQuery:

$('button').on('click', function() {
  $(this).addClass('click');
  // 或?qū)?jQuery 與原生混合使用 `classList`：
  this.classList.add('clicked');
});

NodeList.js:

$$('button').addEventListener('click', function() {
  this.classList.add('clicked');
});

Okay, so the

method of jQuery is quite good. My library uses the browser's native DOM API (hence on), but that doesn't prevent us from creating an alias for the method: addEventListener

$$.NL.on = $$.NL.addEventListener;

$$('button').on('click', function() {
  this.classList.add('clicked');
});

Not bad! This demonstrates how we add our own method:

var nodes = document.querySelectorAll('div');
nodes.forEach(function(node) {
  // do something
});
// 錯誤：nodes.forEach 不是函數(shù)

NodeList.js Support for array methods

NodeList.js does inherit from Array.prototype, but not directly, because some methods have been changed, so it makes sense to use them with NodeList (array of nodes).

push and unshift

For example: push and unshift methods can only take nodes as parameters, otherwise an error will be thrown:

var nodes = document.querySelectorAll('div');
for(var i = 0, l = nodes.length; i < l; i++) {
  // do something with nodes[i]
}

So both push and unshift return NodeList to allow method chaining, meaning it is different from JavaScript's native Array#push or Array#unshift methods, which accept anything and return the array's New length. If we do want the length of NodeList, we just need to use the length property.

These two methods, like JavaScript's native array method, change the NodeList.

concat

concat The method accepts the following as parameters:

[].forEach.call(document.querySelectorAll('div'), function(node) {
    // do something
});

concat is a recursive method, so these arrays can be as deep as we would like to be and will be flattened. However, if any element in the passed array is not a node, NodeList, or HTMLCollection, it will throw an error.

concat Returns a new NodeList, just like the Array#concat method of javascript.

pop, shift, map, slice, filter,

,

Both the popshift and Array#pop methods can take optional parameters, indicating how many nodes to pop or shift from the NodeList. Unlike JavaScript's native Array#shift or

, the latter always pops up or shifts an element in the array regardless of what is passed as a parameter.

map If each mapped value is a node, the

method returns a NodeList; if not, it returns an array of mapped values.

The slicefilter and

methods do the same as they do in real arrays, but return a NodeList.

Array.prototype Since NodeList.js does not inherit directly from Array.prototype, if you add a method to

when loading NodeList.js, it will not be inherited.

You can view the remaining array methods of NodeList.js here.

Special Method

ownerNodeList.js has four unique methods, and a property called prevObject, which is equivalent to the

attribute of jQuery.

getset and

Method:

hrefSome elements have attributes specific to elements of that type (for example, the $$('a').href attribute on the anchor tag). This is why get will return undefined - because it is not a property inherited by every element in NodeList. This is how we use the

method to access these properties:

var nodes = document.querySelectorAll('div');
nodes.forEach(function(node) {
  // do something
});
// 錯誤：nodes.forEach 不是函數(shù)

The

set method can be used to set these properties for each element:

var nodes = document.querySelectorAll('div');
for(var i = 0, l = nodes.length; i < l; i++) {
  // do something with nodes[i]
}

set also returns NodeList to allow method chaining. We can use it in textContent etc. (both equivalent):

[].forEach.call(document.querySelectorAll('div'), function(node) {
    // do something
});

We can also set multiple properties in one call:

var nodes = document.querySelectorAll('div');
nodes.item(0) === nodes[0]; // true

All the above operations can be done using any attribute, for example style:

var buttons = document.querySelectorAll('button'); // 返回瀏覽器無用的 NodeList
for(var i = 0, l = buttons.length; i < l; i++) {
  buttons[i].textContent = 'Click Me';
}

call Method

The

call method allows you to call element-specific methods (for example, pause on a video element):

$('button').text('Click Me');

item Method

The

item method is equivalent to the eq method of jQuery. It returns a NodeList which contains only the nodes passing the index:

$$('button').textContent = 'Click Me';

owner Attributes

The

owner attribute is equivalent to the prevObject of jQuery.

$$('button').set('textContent', 'Click Me');

btns.style returns a style array, while owner will return the NodeList mapped by style.

NodeList.js Compatibility

My library is compatible with all major new browsers as described below.

BrowserversionFireFox6 Safari5.0.5 Chrome6 IE9 Opera11.6 Conclusion

Now we can finally use the useful NodeList object!

For a compression size of about 4k you get all the above and more, which you can learn about in the GitHub repository of NodeList.js.

Since NodeList.js uses a browser as a dependency, no upgrade is required. Whenever the browser adds new methods/attributes to the DOM element, you can use these methods/attributes automatically via NodeList.js. All of this means that the only deprecation you need to worry about is the browser removal method. These are usually very low usage methods because we can't break the web.

So what do you think? Would you consider using this library? Are any important features missing? I'd love to hear your comments in the comments below.

Frequently Asked Questions about DOM Operations with NodeList.js

What is the difference between NodeList and HTMLCollection?

NodeList and HTMLCollection are both node collections. The main difference between them is that NodeList can contain any node type, while HTMLCollection is a collection of element nodes. HTMLCollection is also dynamic, meaning it will be updated automatically when the document structure changes. NodeList, on the other hand, is static and does not update to reflect changes in the document.

How to convert NodeList to an array?

You can convert NodeList to an array using the

method or the expand operator. Here's how to do it:

var nodes = document.querySelectorAll('div');
nodes.forEach(function(node) {
  // do something
});
// 錯誤：nodes.forEach 不是函數(shù)

Why does the jQuery selector return prevObject instead of a normal element?

jQuery's chaining mechanism works by storing previous objects before making changes. This allows you to use the .end() method to restore to your previous state. If you want to get the actual DOM element, you can use the .get() method or array notation.

How to loop through NodeList?

You can loop through the NodeList using the for loop, for...of loop, or forEach() method. Here is an example using a for loop:

var nodes = document.querySelectorAll('div');
for(var i = 0, l = nodes.length; i < l; i++) {
  // do something with nodes[i]
}

What is the use of the .prev() method in jQuery?

The .prev() method in jQuery is used to select the selected element immediately next to the previous sibling. If a selector is provided, the previous sibling element is retrieved only when the selector is matched.

Is jQuery still relevant in 2022?

While jQuery was a game-changer at launch, the modern JavaScript ecosystem has changed significantly. Many of the features that make jQuery popular are now built into JavaScript itself. However, jQuery is still widely used and maintained, and it may be a good choice for some projects.

How to select a specific node from NodeList?

You can select a specific node from NodeList using the array notation or the item() method. Here's how to do it:

[].forEach.call(document.querySelectorAll('div'), function(node) {
    // do something
});

Can I use map, filter, and reduce methods on NodeList?

NodeList is not an array, so it does not have methods like map, filter, and reduce. However, you can convert NodeList to an array and then use these methods.

What is the difference between querySelector and querySelectorAll?

querySelector Returns the first element in the document that matches the specified CSS selector, and querySelectorAll returns the NodeList of all elements that match the CSS selector.

How to check if NodeList is empty?

You can check if NodeList is empty by checking its length property. If the length is 0, NodeList is empty. Here's how to do it:

var nodes = document.querySelectorAll('div');
nodes.item(0) === nodes[0]; // true

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