The term “void” means “empty space” in the dictionary. In programming, when we use this term, it means returning “nothing” or an “empty value“.
What is the void keyword?
If a function is void, it means the function does not give back anything. It’s like functions in JavaScript that absolutely return undefined.
For example:
function person() {
return undefined
}
person()or like this example:
function person() {
}
person()No matter what operations or instructions are included in the functions above (such as adding four numbers or finding the average of 8 numbers), they do not provide any output.
Now that we understand the purpose of the “void” keyword. But what does “javascript:void(0)” mean?
What does javascript:void(0) mean?
If we have divided this, we have javascript: and void(0).
Let’s explore at each part in more specifics.
- javascript:
- This is called a Pseudo URL. When a web browser get this value as the “href” value of a link, it reads the JavaScript code after the colon (:)or rather handling the value as a normal website address.
Here’s an example code:
<a href="javascript:console.log('javascriptSample');alert('javascript Programm Succesfully Sent a Message')">Example Link</a>When you run the code above and click the Example link the output will be:
As you can see in the above example, the browser doesn’t handle href as a regular path. Rather, it manage some JavaScript code and begin after “javascript:” and separated by semi-colons.
- void(0)
- The void operator will check the expressions and gives back an “undefined” result.
Let’s take a look at the example code here:
const adition = void(3 + 3);
console.log(adition);
When we add 3 + 3 together, we get a result, but it is not defined or clear.
Let me show you another example to confirm this:
<body>
<h1>Welcome to JavaScript Void Tutorial</h1>
<script>
void(document.body.style.backgroundColor = 'blue',
document.body.style.color = 'white'
)
</script>
</body>Output:
How to combine “javascript:” and “void(0)” together?
Sometimes, you may not want a link to take you to a another page or refresh the page. By using JavaScript:, you can execute the code that doesn’t change the current page.
If joined with void(0), it is essentially means doing nothing-no refreshing, no navigation, and no execution of any code.
Here’s an example:
<a href="javascript:void(0)">Click the Link Here</a>The word “Link” is regarded as a clickable word in a web browser. It can be preferred, but it does not take you to a different page.
When we pass 0 as an argument to the void function, it does not do anything and isn’t give any result.
You can also pass JavaScript code (like the one shown above) as an argument to the void function.
This enables the link to execute some code while staying on the same page.
Here’s an example code:
<a id="link" href="javascript:void(
document.querySelector('#link').style.color = 'red'
);">Click the Link Here!</a>Output:
When using “void“, it will notify the browser to not show anything or give any result.
Another reason to use “javascript:void(0)” for links is when we want to run some JavaScript code without actually managing to a new page.
In such cases, we use the expressions as arguments with void.
Conclusion
In this article, we learned about the void operator. It helps us avoid a webpage from going to a different page or reloading when we click on a link with the javascript: pseudo URL.
Additional Resources
- What Does Return Do in JavaScript?
- Wait Function JavaScript: The Ultimate Guide
- Exploring Advanced Concepts in Volta JavaScript
Common use cases for JavaScript Void 0: Exploring the Mysteries and Realities
JavaScript Void 0: Exploring the Mysteries and Realities appears in most modern JavaScript codebases. The most frequent patterns:
- Front-end applications. React, Vue, Svelte, and vanilla JS all rely on JavaScript Void 0: Exploring the Mysteries and Realities for user interactions and rendering logic.
- Back-end services. Node.js APIs use JavaScript Void 0: Exploring the Mysteries and Realities in request handlers, middleware, and data pipelines.
- Utility functions. Small reusable helpers wrap JavaScript Void 0: Exploring the Mysteries and Realities to encapsulate common transformations.
- Test suites. Unit tests exercise JavaScript Void 0: Exploring the Mysteries and Realities across happy-path and edge-case inputs to lock behavior.
- Configuration handling. Read from environment variables or config files and normalize with JavaScript Void 0: Exploring the Mysteries and Realities before use.
Working code example
// A realistic example of JavaScript Void 0: Exploring the Mysteries and Realities in production code
function processInput(rawValue) {
// Guard against unexpected input
if (rawValue == null) {
return { ok: false, reason: "empty input" };
}
const cleaned = String(rawValue).trim();
if (cleaned.length === 0) {
return { ok: false, reason: "whitespace only" };
}
return { ok: true, value: cleaned };
}
const result = processInput(" hello world ");
console.log(result); // { ok: true, value: "hello world" }
Best practices when working with JavaScript Void 0: Exploring the Mysteries and Realities
- Use strict mode. Add “use strict” at the top of your files, or use ES modules which are strict by default.
- Prefer const over let. Only use let when you actually reassign. Never use var in new code.
- Add TypeScript. Adopting TypeScript catches many bugs in JavaScript Void 0: Exploring the Mysteries and Realities at compile time.
- Write focused functions. Small functions with a single responsibility are easier to test and reason about.
- Add unit tests. Cover the happy path plus edge cases like empty strings, null, undefined, and boundary numbers.
Common pitfalls with JavaScript Void 0: Exploring the Mysteries and Realities
- Type coercion surprises. == does implicit conversion. Always use === and !== unless you specifically want coercion.
- Hoisting confusion. Function declarations hoist, but const/let do not. Declare before use.
- this binding. Arrow functions inherit this from the surrounding scope. Regular functions do not. Choose deliberately.
- Silent NaN propagation. Math with a NaN value results in NaN. Guard with Number.isFinite() at boundaries.
Official documentation
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Adones Evangelista
Programmer & Technical Writer at PIES IT Solution
Adones Evangelista is a programmer and writer at PIES IT Solution, author of over 900 tutorials and error-fix guides at itsourcecode.com. Specializes in JavaScript, Django, Laravel, and Python error debugging covering ValueError, TypeError, AttributeError, ModuleNotFoundError, and RuntimeError, plus C/C++ and PHP capstone projects for BSIT students.
Expertise: JavaScript · Python · Django · Laravel · Error Debugging · C/C++
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