if not undefined javascript

1if (typeof myVar !== "undefined") {
2    console.log("myVar is DEFINED");
3}

1if (typeof something === "undefined") {
2    alert("something is undefined");
3}

1if(typeof myVar !== "undefined")

1
2function divisors(integer) {
3    let  i, flag = true; 
4       let arr=[];       
5           
6            
7            for(i = 2; i <= integer - 1; i++) {
8                if (integer % i == 0) { 
9                    flag = false; 
10                     arr.push(i)
11                } 
12            }
13            if (flag == true) 
14              console.log(integer + " is prime"); 
15            else
16                console.log(arr)
17}
18console.log(divisors(15))

1if (query){
2   doStuff();
3}