Js save information from a if sats to a function code example

Example 1: elif exist in js?

x = 10;
if(x > 100 ) console.log('over 100')
else if (x > 90 ) console.log('over 90')
else if (x > 50 ) console.log('over 50')
else if (x > 9 ) console.log('over 9')
else console.log('lower 9')

Example 2: javascript if else

var age=20;
if (age < 18) {
	console.log("underage");
} else {
	console.log("let em in!");
}