Unlike the Java™ programming language, the JavaFX™ Script programming language is an expression language. All executable statements are expressions that consist of zero or more inputs followed by zero (or one) outputs. This includes conditionals, loops, and even blocks.

The following demo provides an example:

import java.lang.Math;
import java.lang.System;

var rand = (Math.random() * 100).intValue();
var s:String = null;
if (rand % 2 == 0) {
     s = "rand is even"
} else {
     s = "rand is odd"
};

System.out.println(s);

import java.lang.System;

var nums = [5, 7, 3, 9];
var total = {
     var sum = 0;
     for (a in nums) { sum += a };
     sum;
}

System.out.println("Total is {total} ");

[number1..number2]

import java.lang.System;

var nums = [0..3];
System.out.println(nums == [0,1,2,3]); // prints true

[1..10 step 2]

import java.lang.System;

var nums = [3..0 step -1];
System.out.println(nums == [3,2,1,0]); // prints true

var nums1 = [3..0 ]; 
var nums2 = [3..0 step 1]; 

if (condition1) {
     System.out.println("Condition 1");
} else if (condition2) {
     System.out.println("Condition2");
} else {
     System.out.println("not Condition 1 or Condition 2");
}

import java.lang.System;

var i = 0;
while (i < 10) {
    if (i > 5) {
         break;
    }
    System.out.println("i = {i}");
    i += 1;
} 

The return Expression is the same as found in the Java programming language:

function add(x, y) {
     return x + y;
}

The throw expression is similar to that of the Java Programming language, but only objects extending java.lang.Throwable may be thrown and caught:

import java.lang.Exception;

function foo() {
     throw new Exception("this is a java exception");
}

function bar() {
     throw "just a string";
}

The try and catch expressions are similar to those of the Java programming language, but use JavaFX Script programming language variable declaration syntax:

try {
     throw "Hello";
} catch (s:String) {
     System.out.println("caught a String: {s}");
} catch (any) {
     System.out.println("caught something not a String: {any}");
} finally {
     System.out.println("finally...");
}

The break and continue expressions are similar to those of the Java Programming language, but labels are not supported.

Examples:

import java.lang.System;

function foo() {
    for (i in [0..10]) {
         if (i > 5) {
              break;
         }
         if (i mod 2 == 0) {
              continue;
         }
         System.out.println(i);
    }
}

function bar() {
    var i = 0;
    while (i < 10) {
         if (i > 5) {
              break;
         }
         if (i mod 2 == 0) {
              continue;
         }
         System.out.println(i);
         i += 1;
    }
} 

The JavaFX Script programming language provides standard operators similar to those found in the Java programming language. The following chart lists these operators by precedence, comparing to their Java programming language equivalent.

Examples:

import java.lang.System;
import java.lang.Math;

var x = 2;
var y = 4;
var a = true;
var b = false;
System.out.println(x == y); // prints false 
System.out.println(x <> y); // prints true
System.out.println(x < y);  // prints true
System.out.println(x > y);  // prints false
System.out.println(x >= y); // prints false
System.out.println(x <= y);  // prints true
System.out.println(x + y);  // prints 6
System.out.println(x - y);  // prints -2
System.out.println(x * y);  // prints 8
System.out.println(x / y);   // prints 0
System.out.println(x % y);   // prints 2
System.out.println(a and b); // prints false
System.out.println(a or b);  // prints true
System.out.println(not a);  // prints false
System.out.println(sizeof [x,y]); // prints 2 
System.out.println([x,y][e | indexof e == 0]); // prints [ 2 ]  
System.out.println(if (a) x else y); // prints 2
System.out.println(for(q in [x, y] where q < 3) q); // prints [ 2 ]
System.out.println(Math.max(x, y)); // prints 4
System.out.println("abc".toUpperCase()); // prints ABC 
System.out.println(x); // prints 2