Simple and basic use of switch and if

use switch Methods to determine the age group
Generally, when judging relatively complex conditions, you can use IF Sentence to judge
default: When all parameters do not match Just print default What to do

1.switch Method

<script>
	function message(age) {
    
		let msg = " ",
		switch (true) {
       // here switch(2>1) It can also be executed normally , because 2>1 It's true 
			case age > 60 :
				msg = " The elderly ";
				break;     //break Exit after execution , If it doesn't match   Just move on to the next option   And so on   Execute until the corresponding is matched 
			case age > 40:
				msg = " middle-aged ";
				break;
			case age > 20:
				msg = " youth ";
				break;
			}
			return msg;      //return Return to the age of msg
		}
	console.log(message(67));   // Printout 67 The age group you belong to at the age of 
</script>

1.if Method

function message(age) {
    
		let msg = " ",
		if (age > 60) {
    
		msg = " The elderly ";
		} else if (age > 40) {
    
		msg = " middle-aged ";
		}else if (age > 20) {
    
		msg = " youth ";
		}
		return msg;
}
console.log(message(67));   // Printout 67 The age group you belong to at the age of