Dart by Example: Lexical Scope

Dart is a lexically scoped language.Loops that declare their variable will have a new version of that variable for each iteration.

main() {
  var functions = [];
  for (var i = 0; i < 3; i++) {
    functions.add(() => i);
  }
  functions.forEach((fn) => print(fn()));
}
 

$ dart lexical_scope.dart
0
1
2

Compared to javascript:

var functions = [];
for (var i = 0; i < 3; i++) {
    functions[i] = function() { return i };
}
functions.forEach(function (fn) { console.log(fn())});

$ node lexical_scope.js
3
3
3

by @jryanio | source | license