for_in.md

for-in statement

Overview

for-in is the statement for loop with collection. Basic syntax is as below. var for declaration of a variable is not required when you want to use the variable which is already declared at the outside scope.

for (var e in collection) {
    ...
}

The following objects can be used at the collection part.

• Range object.
• Array object.
• Key-Value object.

See examples below about how to work with each object above.

Examples

Example 1. Range

Code

for (var e in 2..10) {
    System.println(e);
}

Result

2
3
4
5
6
7
8
9
10

Example 2. Range with excluding end

Code

for (var e in 2...10) {
    System.println(e);
}

Result

2
3
4
5
6
7
8
9

Example 3. Array

Code

for (var e in [2,3,4,5,6,7,8,9,10]) {
    System.println(e);
}

Result

2
3
4
5
6
7
8
9
10

Example 4. Array variation (1)

Code

for ([i, j] in [[1,2], [3,4], [5,6]]) {
    System.println("[%{i}, %{j}]");
}

Result

[1, 2]
[3, 4]
[5, 6]

Example 5. Array variation (2)

Code

for ([i, j] in [1, 2, 3]) {
    System.println([i, j]);
}

Result

Note that the result is NOT [1, 2] and [3, null], against your expected.

[1, null]
[2, null]
[3, null]

Example 6. Key-Value object

Code

var obj = { a: 10, b: 100 };
for ([key, value] in obj) {
    System.println("key: %{key} => value: %{value}");
}

Result

key: a => value: 10
key: b => value: 100