1:  function func(){2:      var innerVar = globalVar = 20;    3:  }4:  func();5:  console.log(typeof globalVar);    //输出结果为？

var a ＝ (b = 0);

   1:  function foo() {

   2:      var a, b;

   3:      a = b = 20;    //都是局部变量

   4:  }

//定义三个全局变量
var global_var = 1;
global_novar = 2;  //反模式
(function(){global_fromfunc = 3;  //反模式
})();//企图删除
delete global_var;  //false
delete global_novar;  //true
delete global_fromfunc;  //true//测试删除情况
typeof global_var;  //'number'
typeof global_novar;  //'undefined'
typeof global_fromfunc;  //'undefined'

   1:  function func(){2:      var innerVar = globalVar = 20;    3:  }4:  func();5:  console.log(typeof globalVar);    //输出结果为？

将上述代码稍微修改下又如何呢？

   1:  var person = {

   2:      name: 'casper',

   3:      age: 11

   4:  };

   5:  Object.prototype.getName = function(){};  

   6:  for(var key in person){

   7:      console.log(key);

   8:  }

输出：name输出：age输出：getName

   1:  console.log(typeof un);  //'undefined'

   2:  console.log(typeof deux);  //'undefined'

   3:  console.log(typeof trois);  //'undefined'

   4:   

   5:  var jsstring = "var un  = 1; console.log(un);";

   6:  eval(jsstring);  //logs "1"

   7:   

   8:  jsstring = "var deux = 2; console.log(deux);";

   9:  new Function(jstring)();  //logs "2"

  10:   

  11:  jsstring = "var trois = 3; console.log(trois);";

  12:  (function(){

  13:      eval(jsstring);

  14:  })();  //logs  "3"

  15:   

  16:  console.log(un);  //'number'

  17:  console.log(typeof deux);  //'number'

  18:  console.log(typeof trois);  //'undefined'

   1:  (function(){

   2:      var local = 1;

   3:      eval("local = 2; console.log(local);");  //logs 3

   4:      console.log(local);  //logs 3

   5:  })();

   6:   

   7:  (function(){

   8:      var local = 1;

   9:      new Function("console.log(typeof local);")();  //logs 'undefined'

  10:  })();

本文转自艾伦 Aaron博客园博客，原文链接：http://www.cnblogs.com/aaronjs/p/3164261.html，如需转载请自行联系原作者