Sudoku & widget state
Complete a four-by-four Sudoku grid to explore the state a JavaScript widget manages.
The original navigation included a Sudoku sample. This newly written four-by-four exercise preserves the topic without presenting a recovered game. Fill each row, column and two-by-two box with the digits 1 to 4, once each.
Complete the empty cells, then check the grid.
State stays with the puzzle
The inputs and validation result belong to this example. Values remain in browser memory and reset when the page reloads. This exercise uses ordinary JavaScript; it is not an ADsafe validation or a demonstration of a security boundary.
Read Widget Structure to see how the historic design intended to confine guest code.