← Back toFront-end tips

Put special operators at the beginning of a function

Written byPhuoc Nguyen
23 Feb, 2021
Usually, we can invoke a function by using the form of Immediately Invoked Function Expression (IIFE).
(function (a, b) {
return a + b;
})(4, 2);

// 6
Do you know that we get the same result if we omit the parentheses and put + at the beginning as follow:
+(function (a, b) {
return a + b;
})(4, 2);

// 6
It works because putting `+` at the beginning of function declaration will turn it to an expression, and passing the parameters with `()` at the end will invoke the expression. It is rare to see that code in development, but it is used in the minifications to save the file size. In addition to `+`, you can use other operators such as `-`, `!`, `~` and void in the similar way to invoke a function:
-function() { ... }();
!function() { ... }();
~function() { ... }();
void function() { ... }();
Note that the return value could be different from the original function, for example:
!(function () {
return false;
})(); // true
If you found this post helpful, please consider giving the repository a star on GitHub or sharing the post on your favorite social networks 😍. Your support would mean a lot to me!

Questions? 🙋

Do you have any questions about front-end development? If so, feel free to create a new issue on GitHub using the button below. I'm happy to help with any topic you'd like to learn more about, even beyond what's covered in this post.
While I have a long list of upcoming topics, I'm always eager to prioritize your questions and ideas for future content. Let's learn and grow together! Sharing knowledge is the best way to elevate ourselves 🥷.
Ask me questions

Recent posts ⚡

Newsletter 🔔

If you're into front-end technologies and you want to see more of the content I'm creating, then you might want to consider subscribing to my newsletter.
By subscribing, you'll be the first to know about new articles, products, and exclusive promotions.
Don't worry, I won't spam you. And if you ever change your mind, you can unsubscribe at any time.
Phước Nguyễn