Variable Promotion and function promotion

Variable Promotion and function promotion

1. Variable Promotion

A variable promotion is the promotion of a variable declaration to the very beginning of the scope in which it is located.

2. Function Promotion

There are two ways to create a function, one is a function declaration, one is a function expression, and only a function declaration is a function promotion.

3. Priority of function promotion and variable promotion

The function promotion is higher than the priority of the variable promotion and is not overwritten by the variable declaration, but is overwritten after the variable is assigned a value.

Principle:

Variable Promotion and function promotion