How to Exit from a Function in JavaScript

When you're coding, you sometimes want to exit from the middle of a function.
This is useful for when you want to stop the further execution of the code, or to return a value you have already generated.
In this post, we'll learn how to exit from a function in JavaScript.
How to Exit from a function
Let's say you have a function that takes in two numbers and adds them.
However, you want to exit from the function if either number is negative.
Here's how that looks like:
const sum = (num1, num2) => {
if (num1 < 0 || num2 < 0) {
return -1;
}
return num1 + num2;
}
Notice how we can immediately exit the function by using the return
keyword.
This is a great way to validate that the parameters passed in are valid, or simply to return back the user a value once it has been calculated.
Here's an example of a greeting that requires a name to be passed in.
const greeting = (name) => {
if (!name) {
return "Please pass a name!";
}
return `Hello, ${name}!`;
}
console.log(greeting("John"));
console.log(greeting());
Hello, John!
Please pass a name!
Conclusion
In this post, we learned how to immediately exit a function.
Just use the return
keyword to exit from a function and the rest of the function will not execute.
Thanks for reading!
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