[JavaScript study notes] Process control (JS and C++ are no different, very good, very good!)

During the execution of a program, the execution sequence of each code has a direct impact on the result of the program. Many times we need to control the execution sequence of the code to achieve the function we want to complete.
There are three main structures for process control

• Sequence structure
• Branch structure
• Cyclic structure

Sequential process control

The program will be executed in sequence according to the sequence of the code!

Branch flow control if statement

Judging age

        var age=prompt('input your age:')
        if(age>=18)
            alert('Let us fly');
        else
            alert('can not fly');

Judging Leap Year

        var year=prompt('input the year:')
        if(year%4==0&&year%100!=0||year%400==0){
    
    
            alert('yes');
        }else{
    
    
            alert('no');
        }

Ternary expression

Conditional expression? Expression 1: Expression 2
If the result of the conditional expression is true, return expression 1, otherwise return the value of expression 2

Zero padding case

        var time=prompt('input a number:')
        console.log(time<10?'0'+time:time);   

Branch flow control switch statement

        var fruit=prompt('input your fruit:')
        switch(fruit){
    
    
            case 'apple':
                alert('the price is 3.5');
                break;
            case 'pear':
                alert('the price is 35');
                break;
            default: 
                alert('there is no kind of this furit！');
        }