Comments and Scope - Dart Programming

A // comment is reader-only text that Dart skips at runtime. Each { ... } block introduces a new scope: a var declared inside disappears at the closing brace, while names from the enclosing scope stay visible.

Program

Play the program to enter an if block, build a label from inner state, then watch that inner name go out of scope.

comments_scope.dart

void main() {
  var label = 'outer';
  // a reader-only comment; this does not run
  if (label == 'outer') {
    var detail = 'inner';
    label = '$label/$detail';
  }
  print(label);
}

// comment Lines starting with `//` are for readers only; Dart skips them at runtime.

block scope `var detail` declared inside the `{ ... }` block exists only there; the outer `label` stays visible.

after the brace Past the closing `}` `detail` is gone, but `label` keeps its updated value.