node.js - 从 forEach 内部的 while 中中断

Question

你好，我必须打破 while 循环。在那个 while 循环中，我正在调用一个异步函数。我必须检查该异步调用的输出中的某个字段是否为空，然后我必须中断，否则我将再次调用该异步函数。我已经尝试过这个:

var options = {
      headers : {
         'Fk-Affiliate-Id':'xxxxxxx' ,
         'Fk-Affiliate-Token' : 'xxxxxxxxxxxxxxxx'
      }
   };
var state = ['approved','tentative','cancelled','disapproved'];
state.forEach(element => {
  options.url = 'https://affiliate-api.flipkart.net/affiliate/report/orders/detail/json?startDate='+startDate+'&endDate='+endDate+'&status='+element+'&offset=0';
    loop : while(true){
        // This is the async call
        request.get(options, (err, res, body) => {
          var data = JSON.parse(body);
          console.log(data);
          // I have to check whether next is empty or not ?
          if(data.next === ''){
            // I will perform some action on data here
            break loop;
          }
          else{
            // I will perform some action on data here
            options.url = data.next;
          }
        });
      }
});

但这显示错误非语法中断。如何打破 while 循环？

Answer 1

似乎你不需要 while 循环。当您达到某一状态的所需结果时，您只想停止。这意味着您需要等到异步调用完成，然后才能继续另一个状态。解决方案之一是使调用同步(如果可能)。另一个解决方案是为每个状态处理创建单独的函数，并从异步调用回调中调用它:

var state = ['approved','tentative','cancelled','disapproved'];
// starting with first state
processState(0);

function processState(stateIdx){
    if(stateIdx >= state.length){
        // we tried all states and no success.
        return;
    }
    // some code
    request.get(options, (err, res, body) => {
        // some code
        if(data.next !== ''){
            // we have more records for this state - call it one more time.   
            processState(stateIdx);
        } else {
            // done with this state, try next one.   
            processState(stateIdx + 1);
        }
    });
}