Check wether a condition is satisfied:
var n1 = 0; var n2 = 0; for (var i=1; i<=10; i++) { if (arr[i] % 2 ==0 ) n2 += arr[i]; else n1 += arr[i]; }
Check a value is true or false (false can be represented as 0, false, undefined, null, NaN or ""):
var x=true; if (x) alert("true") if (y) alert("true") // y is undefined
Use
for (var i=1; i<14; i++) { if (arr[i] % 2 == 0 && (arr[i] % 3 == 0 || arr[i] % 5 == 0)) alert(arr[i]); //6, 10 }
If () {...} else if (){...} else {...}:
for (var i=1; i<10; i++) { if (arr[i] % 2 == 0) { alert("2"); //2,4,6,8 } else if (arr[i] % 3 == 0) { alert("3"); //3,6,9 } else alert("other"); //1,5,7 }