import 'dart:convert' show JSON;
void main() {
// NOTE: Be sure to use double quotes ("),
// not single quotes ('), inside the JSON string.
// This string is JSON, not Dart.
var jsonString = '''
[
{"score": 40},
{"score": 80}
]
''';
var scores = JSON.decode(jsonString);
assert(scores is List);
var firstScore = scores[0];
assert(firstScore is Map);
assert(firstScore['score'] == 40);
}