Memory management, event delegation, and code splitting
Applications developed in advanced web development in JavaScript programming should be equipped with user system compatible, efficient, and globally scalable features. To design advanced user compatible web development applications, the system environment should be compatible with memory management, event delegation, and program source code splitting concepts. Here your memory management, event delegation, and program source code splitting concepts help to improve user application behaviour, system performance, responsiveness, and application system resources management allocation.
Memory Management in JavaScript Programming.
Memory management in JavaScript web and application development helps the user to allocate and de-allocate memory resources to objects in JavaScript applications efficiently. The garbage collection features of JavaScript programming manage and control most of the memory management automatically. For this, the user has to understand the memory management concept, so that the user can manage the memory and prevent memory leakage and improve the system performance.
Garbage Collection in JavaScript.
JavaScript programming follows an automatic garbage collection structure mechanism concept for memory management. Where the JavaScript engine strictly watches the memory usage, and automatically clears those system application objects, which are no longer being used in the system garbage storage, or are not present in the system reference.
Garbage Collection Features.
- Reference counting – In JavaScript programming, when no other object reference points to that object, it is de-allocated in the system.
- Mark-and-sweep – JavaScript applies this algorithm to select and mark some objects that are still accessible or compatible in the system, after which it empties the memory storage held by all these objects, which are not yet accessible or compatible with the user.
Common causes of memory leaks in JavaScript programming.
- Global variables – Sometimes in the JavaScript program execution process, variable data types are stored in global scope nature, and if they are not cleared properly in the garbage collection erase process, then it can sometimes be the cause of memory leaks in the system.
- Detached DOM elements – Sometimes in a JavaScript program, there are objects or elements that are removed from the DOM, which still have event listeners or their previous references, so sometimes garbage collection is not possible in them.
- Closures – Closures in JavaScript programs sometimes hold object and program variable references for longer than necessary than external functions, due to which they can be the cause of memory leaks.
Best practices of memory management in JavaScript.
- Avoid global variables – Avoid global variables in the program or declare variables in local scope function modules as far as possible.
- Null references to large objects – When objects or arrays are not needed in a large JavaScript program, set them to null or undefined data type.
- Remove event listeners – When event listeners are not needed in a JavaScript program, remove them first, especially for those DOM elements which are removed when needed.
/// here we remove existing event listeners to prevent system memory leaks
const testelement = document.getElementById(“testElement”);
function testClick() {
console.log(“test Element hit”);
}
// we Add here an event listener
testelement.addEventListener(“click”, testClick);
// here we Remove the event listener when the element is no longer required
testelement.removeEventListener(“click”, testClick);
Event Delegation in JavaScript.
Event delegation is a popular concept in JavaScript programming, where JavaScript programmers add a single event listener to a parent element instead of adding a separate event listener to each child element as needed. This process can improve system performance, especially when dealing with large volumes of elements, and where it helps to add or remove child elements in a dynamic order without rebinding the event listener.
Why use event delegation in JavaScript?
- Performance – Adding event listeners to child elements in a JavaScript program can sometimes slow down the web browser, especially when working with large lists or dynamic content.
- Dynamically added elements – This allows JavaScript programmers to automatically assign event listeners to newly added elements in the order it needs to be added without having to rebind the event.
How event delegation works in JavaScript.
Instead of adding an event listener to each child element in a JavaScript program, we attach the event listener to the parent element.
When an event is triggered in a JavaScript program, it “bubbles” it from the target element to the parent element, where the parent element can decide whether to manage or handle the event based on the target element.
Example of how event delegation works.
<ul id=”sampleList”>
<li>Sample lit 1</li>
<li>Sample lit 2</li>
<li>Sample lit 3</li>
<li>Sample lit 4</li>
</ul>
<script>
// here we Attach the event listener to the parent <ul> html tag element
const list = document.getElementById(“sampleList”);
list.addEventListener(“click”, function(event) {
// here we use it to Only handle click on <li> list tag elements
if (event.target.tagName === “LI”) {
alert(`let click to select ${event.target.textContent}`);
}
});
</script>
Benefits of event delegation in JavaScript.
- It provides better program performance by reducing the number of event listeners in the program.
- It uses less memory, as here users are grouping only one event listener.
- It manages the dynamic content in the program, triggering the event listener automatically every time a newly added element is added.
Code splitting in JavaScript.
Code splitting is a concept in JavaScript programming that involves splitting a large volume program source code bundle into smaller “module” pieces that can be loaded into the program as needed. Code splitting greatly improves the performance of system web applications by reducing the initial program load time and loading only the necessary program source code.
Why use code splitting in JavaScript?
- Faster initial load – It reduces the amount of JavaScript source code required at the time of initial open load of a webpage in a web browser.
- Improved performance – When accessing particular features in a program or webpage, it loads only the program source code required for it.
- Improved user experience – It allows the user to start interacting with the app faster in the existing application without having to wait for the complete app to load.
How code splitting works in JavaScript.
- Dynamic imports – Here you can apply the import() function method to load program source code blocks in a dynamic format only when needed, instead of loading everything in advance in a system.
- Bundlers – Using import tools like Webpack Parcel or Rollup in JavaScript webpages can automate program source code splitting by splitting the program source code into multiple source code bundles.
Example of Webpack in JavaScript.
In a JavaScript webpage, programmers want to split the code of a feature that is used only in a specific webpage.
// here we create a code in In main.js file
document.getElementById(“loadFeatures”).addEventListener(“click”, () => {
import(“./features.js”).then(module => {
// here we Use the dynamically imported module features for code splitting
module.loadFeatures();
});
});
In this example, when the user manually clicks on the loadFeatures button, the program code of features.js will load in dynamic format only at that time. Because of this, the initial JavaScript source bundle remains in small pieces, and it increases the webpage loading time in the web browser.
Use of Webpack for code splitting in JavaScript.
In JavaScript programming, Webpack splits the JavaScript program source code into multiple parts in a dynamic format automatically. Here is an example of Webpack configuration for code splitting.
module.exports = {
entry: ‘./src/index.js’,
output: {
filename: ‘[name].[contenthash].js’,
chunkFilename: ‘[name].[contenthash].js’,
path: path.resolve(__dirname, ‘dist’)
},
optimization: {
splitChunks: {
chunks: ‘all’, // here This code split all types of webpage source code into small modules
},
},
};
Here this is a common library in the program, which will create multiple split blocks for vendor source code and modules imported in dynamic format.
Memory management, event delegation, and code splitting Summary.
| Concept | Description or definition | advantage | Where to use |
| Memory Management features | It Refers to efficient allocation and cleanup of memory in JavaScript program, primarily it managed and controlled by garbage collection features. | It Prevent memory leaks in system, and improve system performance. | It used to deal large apps with complex source code logic. |
| Event Delegation features | It used to Attaching a single event listener to a parent element in webpage to handle multiple events on its children, rather than attaching listeners to each child element may be cause page source delay. | It helps to optimize better system performance, and handles dynamic web content. | It able to manage or Handling events in large lists or dynamic elements or object. |
| Code Splitting features | It used to Breaking up large volume JavaScript bundles source code into smaller chunks code that are loaded as needed as user requirement. | It helps you to Faster webpage load times and avoid any delays, instant improved system performance. | It Applications with multiple features or routes in application. |
Main advantages of code splitting in JavaScript.
- Smaller bundle size – In code splitting method, only the required program source code is loaded initially, due to which the size of the initial program bundle is reduced.
- Faster load time – By loading program source code when needed, a web browser can render initial web content faster, improving webpage loading performance.
- On-demand loading – This loads essential features of a webpage only when the Internet user wishes to interact with them, such as when the user navigates to a specific webpage or clicks a button.
