如何在 JavaScript 中重新抛出异常，但保留堆栈？

每当抛出异常时，堆栈跟踪都会传达部分数据。堆栈跟踪是程序中使用的所有方法的集合。它以引发异常的方法开始，以捕获异常的方法结束。如果重新抛出异常，堆栈跟踪将在当前方法处重新启动。因此，抛出异常的方法和当前方法之间的方法调用列表会丢失。避免这种情况的一种方法是捕获错误并将其存储在本地，然后重新抛出错误。但是，在 JavaScript 中，没有 rethrow()函数。于是我们就抛出了原来的错误。要了解上述上下文，请参阅以下示例。

示例 1：在课堂测试中，Radha 应该回答老师提出的问题。老师给 Radha 一个数字，并询问她给定的数字是否是有效的日期，如果是，则指定相应的日期。如果给定的日期编号无效，Radha 应该回答“无效的日期编号”。如果我们运行代码，嵌入页面将显示堆栈跟踪。它将显示错误源自 day()，然后在 month() 重新抛出，最后在 year() 中捕获。由于 8 超出范围，因此输出显示为 Invalid day。

Input: 8 
Output:Error originated in day() and was thrown
 Invalid day
 Error was caught and rethrown in month()
 Invalid day
 Error was finally caught in year()
 Invalid day

• 程序：

    
  
      
          year();
            
          // For the year //
          function year() {
              try {
                  month();
    
              } catch (e) {
                  console.log(
  'Error was finally caught in year():', e.message);
                  alert(e.stack);
              }
          }
    
          // Fo the month //
          function month() {
              try {
                  day();
              } catch (e) {
                  console.log(
  'Error was then caught and rethrown in month():', e.message);
                  throw (e);
              }
          }
    
          function day() {
              var d = 8;
              var days = [
                'Mon', 'Tue', 'Wed', 
                'Thurs', 'Fri', 'Sat', 'Sun'];
              try {
                  d = d - 1;
                  if (days[d] != undefined)
                      console.log("valid day:", days[d]);
                  else
                        
                      // Message is "Invalid day"
                      throw new Error("Invalid day"); 
              } catch (e) {
                  console.log(
  "Error originated in day() and was thrown:", e.message)
                  throw (e);
    
              }
          }
      
  
    
  
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• 输出：

  Error originated in day() and was thrown:
   Invalid day
   Error was then caught and rethrown in month():
   Invalid day
   Error was finally caught in year():
   Invalid day

示例 2：数字 5 是有效的天数，因此不会引发错误。因此，我们将输出作为有效日期。

Input: 5
Output:
valid day:
Fri

程序：

  

    
        year();
  
        function year() {
            try {
                month();
  
            } catch (e) {
                console.log(
'Error was finally caught in year()', e.message);
                alert(e.stack);
            }
        }
  
        function month() {
            try {
                day();
            } catch (e) {
                console.log(
'Error was caught and rethrown in month()', e.message);
                throw (e);
            }
        }
  
        function day() {
            var d = 5;
  
            var days = [
              'Mon', 'Tue', 'Wed', 
              'Thurs', 'Fri', 'Sat', 'Sun'];
            try {
                d = d - 1;
                if (days[d] != undefined)
                    console.log("valid day:", days[d]);
                else
                    throw new Error("Invalid day");
            } catch (e) {
                console.log(
"Error originated in day() and was thrown:", e.message);
                throw (e);
  
            }
        }
    

  

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输出：

valid day:
 Fri