JS-一 _JavaScript

JS-1

在线学习网站非常cool 能够满足自我挑战的感觉资料也是最新的

很喜欢

JS中唯一不是true的东东都在这儿了:(

function sad(value) {
  // If a value is falsy, return the string ':('.
  // Otherwise, don't return anything.
  if(!value) {
      return ':(';
  }
  
  return;
}

console.log(sad(undefined));
console.log(sad(false));
console.log(sad(""));
console.log(sad(0));
console.log(sad(NaN));
console.log(sad(null));

JS中提倡使用===和!==来进行等价判断与equalReference和equalValue类似

// difference between == and ===
// remember always use === and !==
console.log(null == undefined);
console.log(null === undefined);