的NodeJS - 使while循环同步 [英] NodeJS - making the while loop synchronous

问题描述

我有如下一段code的

  VAR页= 2;
VAR last_page = 100;
而（页面＆LT; = last_page）{
  请求（http://some_json_server.com/data?page=+页，功能（错误，响应体）{
    如果（误差放大器和;！＆安培; response.status code == 200）{
      store_data（体）
    }
    ++页面;
  }）;
}
 

我已经做以下，但实际上没有任何东西取回。我在做正确吗？

  VAR页= 2;
VAR last_page = 100;
而（页面＆LT; = last_page）{
变种async_arr = [];
async_arr.push（
  功能（下）{
    请求（HTTP：// some_api_url页=+页，功能（错误，响应体）{
      如果（误差放大器和;！＆安培; response.status code == 200）{
        store_data（体）;
      }
    }）;
  }
）;async.series（
  async_arr，做
）;
 

解决方案

您正在寻找 async.whilst（）。该解决方案是假设你真正想做的事情后，其他每个请求。由于@UpTheCreek提到（的修改的：我所指被编辑评论）它可能会是可能的异步做，跟踪使用每个结果的 async.parallel 。

  VAR页= 2，
    末页= 100;async.whilst（函数（）{
  返回页面＆LT; =末页;
}，
功能（下）{
  请求（http://some_json_server.com/data?page=+页，功能（错误，响应体）{
    如果（误差放大器和;！＆安培; response.status code == 200）{
      store_data（体）
    }
    ++页面;
    下一个（）;
  }）;
}，
功能（错误）{
  //所有的事情都做了！
}）;
 

I've got a following piece of code

var page = 2;
var last_page = 100;
while(page <= last_page) {
  request("http://some_json_server.com/data?page=" + page, function (error, response, body) {
    if (!error && response.statusCode == 200) {
      store_data(body)
    }
    page++;
  });                
}

I've done the following, but it is actually not retrieving anything. Am I doing this correctly?

var page = 2;
var last_page = 100;
while(page <= last_page) {
var async_arr = [];
async_arr.push(
  function(next) {
    request("http://some_api_url?page=" + page, function (error, response, body) {
      if (!error && response.statusCode == 200) {
        store_data(body);
      }
    });
  }
);

async.series(
  async_arr, done
);

解决方案

You're looking for async.whilst(). This solution is assuming you actually want to do each request after the other. As @UpTheCreek mentions (edit: the comment I referred to was edited) it would likely be possible to do it asynchronously and keep track of each result using async.parallel.

var page = 2,
    lastPage = 100;

async.whilst(function () {
  return page <= lastPage;
},
function (next) {
  request("http://some_json_server.com/data?page=" + page, function (error, response, body) {
    if (!error && response.statusCode == 200) {
      store_data(body)
    }
    page++;
    next();
  });
},
function (err) {
  // All things are done!
});

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