JS: “function” (keyword) name hoisting

Function Declaration Hoist Name and Value

for functions defined by the keyword function, there are these complex issues:

• If it is written as a function declaration, it implicitly move the function name and definition to the top. (known as name-hoisting.)
• If it is written as a function expression assigned to variable by the keyboard var, then, only hoist the name, not the definition.

Compare:

console.log(ff());
// prints
// 3

function ff() {
 return 3;
}

console.log(gg());

var gg = function gg() {
 return 3;
};

// error: Uncaught (in promise) ReferenceError: Cannot access 'gg' before initialization