在这个javascript中有没有竞争条件？ [英] is there a race condition in this javascript?

问题描述

在以下js代码段

request = new XMLHttpRequest
request.open('GET', '/my/url', true)
request.send()

request.onload = function() {
  data = JSON.parse(this.response)
}

如果负载的分配在send（）之前，以避免竞争条件。

should the assignment of the on load be before the send() to avoid a race condition. Or does the browser deal with it for you (by firing the on load when you get round to assigning it).

推荐答案

您的浏览器可以处理您的邮件请求应该看起来更像：

Your request should look more like:

var request = new XMLHttpRequest || new ActiveXObject('Microsoft.XMLHTTP');
request.open('GET', '/my/url');
request.onreadystatechange = function(){
  if(request.readyState == 4 && request.status == 200){
     console.log(request.responseText);
  }
}
request.send();

要进一步回答您的问题 request.send（）应该最后发生，因为如果响应回来之前函数被分配到 request.onreadystatechange ，可能有一个问题，虽然不太可能的响应将是那快。

To further answer your question request.send() should happen last, because if the response comes back before the function is assigned to request.onreadystatechange, there could be a problem, although it's very unlikely that the response would be that fast.

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