if/else | NN 2 IE 3 ECMA 1
This is a conditional statement that provides two execution paths depending on the result of the condition. You can nest another if or if/else statement inside either path of the if/else statement.
Example
    var theMonth = myDateObj.getMonth( );
    if (theMonth == 1) {
        monLength = calcLeapMonthLength( );
    } else {
        monLength = calcMonthLength(theMonth);
    }