结合两个变量设置一个新变量使用javascript设置一个已经声明的变量

Question

我想通过组合两个变量，一起使原始变量的名称设置一个新的变量与已经声明的变量相同的值。这可能听起来令人困惑，所以这里有一个例子：

// JavaScript Document 


document.write (finalVar); 

$(document).ready(function() 
{ 
var position_1 = $("#box_1").position(); 
var left_1 = position_1.left; 
var top_1 = position_1.top; 
var position_2 = $("#box_2").position(); 
var left_2 = position_2.left; 
var top_2 = position_2.top; 
var box; 
var boxLength; 
var boxNumber; 
var selected = 0; 


$("#box_1").click 
    (function() 
     { 
      if (selected == 1) // if a box is selected run the following 
       {  
        box = $(".selected").attr("id"); 
        boxLength = box.length; 
        boxNumber = box.charAt(boxLength-1); // finds the number of the box 
        alert(+boxNumber); 
       if (box == "box_1") // if the selected box is itself  then mimimise the box, remove the selected class from it and set selected to zero 
        { 
         $("#box_1").animate({height:50,opacity:0.8,left:left_1,top:top_1,borderRadius:4,MozborderRadiu s:4},(60),"swing").animate({width:50},(60),"swing").animate({opacity:0.6},(150),  function() 
         { 
           $(this).removeClass("selected"); 
         }); 
        selected = 0; 
        } 
       else 
        { 
         $(".selected").animate({height:50,opacity:0.8,left:left_+boxNumber,top:top_+boxNumber,borderRadius:4,MozborderRadius:4},(60),"swing").animate({width:50},(60),"swing").animate({opacity:0.6},(150),  function() 
         { 
          $(".selected").removeClass("selected"); 
          $("#box_1").animate({width:900,left:60,top:0,borderRadius:10,MozborderRadius:10},(60),"swing").animate({height:500},(60),"swing").animate({opacity:1},(150), function() 
           { 
            $("#box_1").addClass("selected"); 
           }); 
         } 
       );} } // end of function for if a box is selected 
      else // if no box is selected run the following 
       { 
        $("#box_1").animate({width:900,left:60,top:0,borderRadius:10,MozborderRadius:10},(60),"swing").animate({height:500},(60),"swing").animate({opacity:1},(150), function() 
         { 
          $("#box_1").addClass("selected"); 


         }); 
        selected = 1; 
       } 
     }); 

    $("#box_2").click 
    (function() 
     { 
      if (selected == 1) // if a box is selected run the following 
       {  
        box = $(".selected").attr("id"); 
        boxLength = box.length; 
        boxNumber = box.charAt(boxLength-1); // finds the number of the box 
        alert(+boxNumber); 
       if (box == "box_2") // if the selected box is itself then mimimise the box, remove the selected class from it and set selected to zero 
        { 
         $("#box_2").animate({height:50,opacity:0.8,left:left_2,top:top_2,borderRadius:4,MozborderRadius:4},(60),"swing").animate({width:50},(60),"swing").animate({opacity:0.6},(150), function() 
         { 
           $(this).removeClass("selected"); 
          selected = 0; 
         }); 
        } 
       else 
        { 
        $(".selected").animate({height:50,opacity:0.8,left:left_+boxNumber,top:top_+boxNumber,borderRadius:4,MozborderRadius:4},(60),"swing").animate({width:50},(60),"swing").animate({opacity:0.6},(150),  function() 
         { 
          $(".selected").removeClass("selected"); 
          $("#box_2").animate({width:900,left:60,top:0,borderRadius:10,MozborderRadius:10},(60),"swing").animate({height:500},(60),"swing").animate({opacity:1},(150), function() 
           { 
            $("#box_2").addClass("selected"); 
           }); 
         } 
       );} } // end of function for if a box is selected 
      else // if no box is selected run the following 
       { 
        $("#box_2").animate({width:900,left:60,top:0,borderRadius:10,MozborderRadius:10},(60),"swing").animate({height:500},(60),"swing").animate({opacity:1},(150), function() 
         { 
          $("#box_2").addClass("selected"); 
          selected = 1; 
         }); 
       } 
     }); 

}); 

话，我想5到写入文件......有没有这样做的方法吗？我知道这可能不是正确的方式，甚至开始考虑这样做，我只是用它作为我正在尝试做的同义词。

感谢您的帮助。

Answer 1

如果这些全局变量，你可以做这样的：

var position = 4; 
var a = "posi"; 
var b = "tion"; 

document.write(window[a+b]); 

这仅是因为所有的全局变量实际上是window对象的属性，你可以参考window对象无论是作为window.position的性质或window["position"]。由于后者的工作原理，您还可以使用字符串操作构建字符串"position"，如上例所示。

我会问你为什么这样做？一个常见原因有人问要做到这一点，使他们能够访问诸如position1，position2等变量....如果是这样的话，那么更好的答案是使用可以通过索引访问数组：

var positions = [1,4,67,99]; 

document.write(positions[3]); 

如果您所描述的现实问题

var positions = [1,4,67,99]; 

for (var i = 0; i < positions.length; i++) { 
    document.write(positions[i]); 
} 

：

您可以通过访问变量数组值过这样的：

var positions = [1,4,67,99]; 
var pos = 3; 

document.write(positions[pos]); 

或者，遍历整个阵列上你正在努力解决，我们可以推荐最好的解决方法。你目前问到的问题听起来像是对任何问题的错误处理方式。

Answer 2

我不知道你为什么这样做，但是可以使用eval方法。

试试这个

var position = 5; 
var pos = "posi"; 
var tion = "tion"; 
var finalVar = pos+tion; 

document.write (eval(finalVar)); 

DEMO

Answer 3

利用这一点的同时结合你的变量parseInt函数（POS）+ parseInt函数（银行足球比赛） 不要忘记声明字符串变量POS和银行足球比赛... :)

Answer 4

var position = 'top'; 
var pos = "posi"; 
var tion = "tion"; 
var finalVar = pos+tion; 

alert(window[finalVar]); // better that `eval()` 
document.write(window[finalVar]);