Coffeescript重试循环不起作用

Coffeescript retry loop doesn't work

本文关键字：不起作用 循环 重试 Coffeescript      更新时间：2023-09-26

我有一个这样的循环，如果ajax请求成功，它应该返回并退出循环，它也应该只重试10次，但它只是迭代循环10次，然后在请求成功时停止。

retryCount = 0
while (retryCount < 10)
  $.ajax
    type: "GET"
    url: "http://" + proxyURL + "?"
    dataType: "jsonp"
    data:
      url:
        url + "?" + method + "&" + $.param
          parameters: JSON.stringify parameters
    success: (response) ->
      data = response
      console.log "----------"
      console.log "METHOD: " + method
      console.log parameters
      console.log data
      console.log "----------"
      if data.contents.fault
        if data.contents.fault.code is 256
          console.log "fetching new token (" + retryCount + ")"
          fetchNewToken ->
            return callback(data.contents.result)
        else
          console.log "ERROR: " + $.trim(data.contents.fault.message)
      if data.contents.result
        if data.contents.result instanceof Array
          if data.contents.result.length > 0
            return callback(data.contents.result)
        else
          return callback(data.contents.result)
      else
        console.log "retrying " + method + " (" + retryCount + ")"
    retryCount++

看来你没有理解异步编程的概念。

结果如下:

retryCount = 0
# TIMESTAMP 0
while (retryCount < 10)
  # TIMESTAMP 1, 3, 5, ...
  $.ajax
    url: "http://" + proxyURL + "?"
    dataType: "jsonp"
    success: (response) ->
      #TIMESTAMP very later, long after your loop is through
  # TIMESTAMP 2, 4, 6, ...
  retryCount++

它应该看起来像这样(只是一个例子，有点伪代码):

retryCount = 0
loadData = (retryCount, callBack, errorCallBack) ->
  $.ajax
    url: "asdasdasd"
    success: () ->
      callBack someDataYouRecieved
    error: () ->
      retryCount++
      if retryCount is 10
        errorCallBack "got 10 errors"
      else
        loadData retryCount, callBack

loadData retryCount, successHandler, errorHandler

如果我理解正确的话，这样的结构应该可以达到这个目的(省略了特定于领域的部分):

MAX_RETRIES = 10
issueRequestWithRetries = (request, retries=0) ->
  request.success = (response) ->
    # do something, then find out that you need to retry
    if retries < MAX_RETRIES
      issueRequestWithRetries(request, retries+1)
    else
      # handle the error
  $.ajax request
# sample usage
issueRequestWithRetries
  type: "GET"
  url: "http://" + proxyURL + "?"
  dataType: "jsonp"
  data: {} # real data
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