fortunehan

void main(){
  List? list;
  print(list?.length); // would not throw null exception, just print null
  print(list?.length??0); // 0
}

fortunehan

void main() {
  var student = Student('tie', 'li si', 2);
  print(student.name); // zhang san
  print(student.country); // China
  print(student.age);

  var enigeer = Enigeer('dart', 'wang er', 34);
  print(enigeer.name);
  enigeer.walk(); // call the mixin walk's method
  

fortunehan

void main(){
  List list = ['a','b',2];
  
  Map map = {'name':'san','age':2};
  
  print('***loop map***');
  map.forEach((k, v) => print("Key : $k, Value : $v"));
  
  print('***loop map by keys***');
  map.keys.forEach((k) => print("Key : $k"));

fortunehan

void main(){
  dynamic x = 'foo';
  print(x is String);
  print(x.runtimeType);
  
  x = 123; // no compile error
  print(x.runtimeType);
  
  var y = 'bar';
  print(y.runtimeType);

fortunehan

span.rm-page-ref[data-tag="Resonance"]::before {    
  content: '🧠';    
  display: inline-block;    
  width: 10px;    
  border-radius: 40px;    
  height: 10px;    
  margin-right: 10px;
}

span.rm-page-ref[data-tag="Book"]::before {    

fortunehan

boolean: 
    - TRUE  #true,True 都可以
    - FALSE  #false，False 都可以
float:
    - 3.14
    - 6.8523015e+5  #可以使用科学计数法
int:
    - 123
    - 0b1010_0111_0100_1010_1110    #二进制表示
null:

fortunehan

H1

H2

H3

H4

H5

H6

列表

• 第一项
• 第二项

fortunehan

‎‎​

fortunehan

快捷键

新开一个tab预览当前MD, preview MD cmd+shift+v

设置js工程 jsconfig.json

https://code.visualstudio.com/docs/nodejs/working-with-javascript

{
  "compilerOptions": {
 "module": "commonjs",

fortunehan

npm list -g --depth 0

npm config set registry https://registry.npm.taobao.org
npm config get registry

npm install express --registry https://registry.npm.taobao.org