Interview question bank-pink

1. js basic questions

1. The difference between num++ and ++num / specific expression to find the result

2. Short-circuit operation (logic interrupt) log(0&&num++)

        Return the decimal value, formula, and simple operation result that determine the result of the expression; the following formula is no longer num++

3. Pre-parse the js engine to pre-parse and then execute the code

        Determine whether the code reports an error, and output the result of the scope chain: Note that the variables in the undeclared function are global variables.

                var a=b=9; In the function, b is a global variable and a is a local variable

                

        What code is equivalent to: put the declaration at the front of the current scope, and copy the others.