js运算符–2

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js运算符–2

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>新建网页</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name="description" content="布尔教育 http://www.itbool.com" />
</head>
    <body>
     <script>
     //js中拼接运算符 “ + ”
      console.log(2 + 3);
      console.log('hello' + ' ' +'world');
      console.log(2 + 3 +'haha' + 5 + 6);//一旦碰到非法数字运算后，后面一律理解为“拼接”。
           //js中，逻辑运算符，返回的是最早判断表达式的那个值。
      var a = false;
      var b = 6;
      var c = true;
      var d = (a || b || c );
      console.log(d);
           
      var e = false;
      var f = 99;
      console.log(e && f);
      //window.hello = window.hello || window.world;     if  else判断
     </script>
    </body>
</html>