What is function hoisting in JavaScript?

What is function hoisting in JavaScript?

Function hoisting is a JavaScript mechanism where function declarations are moved to the top of their containing scope during compilation.

Can you give me an example of function hoisting?

Sure! Here's an example:

console.log(myFunction()); // Outputs: 'Hello'

function myFunction() {
    return 'Hello';
}

In this case, myFunction can be called before its declaration.

Does hoisting apply to variables as well?

Yes, variable declarations are also hoisted, but only the declaration, not the initialization. For example:

console.log(myVar); // Outputs: undefined
var myVar = 5;

Here, myVar is hoisted but its value is not assigned until the line where it's initialized.

Are there any exceptions to function hoisting?

Yes, function expressions (like those assigned to variables) are not hoisted in the same way. For example:

console.log(myFunc()); // TypeError: myFunc is not a function
var myFunc = function() {
    return 'Hello';
};

In this case, myFunc is hoisted as a variable but not as a function.