如何停止两次打印循环的输出 [英] How can I stop the output of a loop being printed twice

问题描述

我想制作一个程序，列出太空人的名单。







这就是我想要的输出：



name1 name2 name3



但结果如下：



name1 name2 name3 name1 name2 name3



我该怎么办？

谢谢



我的尝试：

I want to make a program that gives a list of the people in space.



This is what i want the output to be like:

name1 name2 name3

but this is the result:

name1 name2 name3 name1 name2 name3

What do i do?
thanks

What I have tried:

<div id="space_astronauts">
    <span id="child_1"></span>
</div>

var space = new XMLHttpRequest();
space.open("GET", "http://api.open-notify.org/astros.json", "jsonp");
space.send(null);
space.onreadystatechange = function() {
	var res = JSON.parse(space.response);
	
	var totalPeople = res.number;
	for (i = 0; i < totalPeople; i++) {
		var pElement = document.getElementById("space_astronauts");
		var firstChild = pElement.firstChild;
		var astronautsElement = document.createElement("a");
   		var txt = document.createTextNode(res.people[i].name + " ");
   		astronautsElement.appendChild(txt);

   		pElement.insertBefore(astronautsElement, firstChild);
   	}
}

推荐答案

if（this.readyState == 4& & this.status == 200）{

响应中缺少上述条件，导致数据打印两次。

if (this.readyState == 4 && this.status == 200) {
the above condition is missing in the response, which leads to print the data twice.

var space = new XMLHttpRequest();
       space.open("GET", "http://api.open-notify.org/astros.json", "jsonp");
       space.send(null);
       space.onreadystatechange = function () {
           if (this.readyState == 4 && this.status == 200) {
               var res = JSON.parse(space.response);

               var totalPeople = res.number;
               for (i = 0; i < totalPeople; i++) {
                   var pElement = document.getElementById("space_astronauts");
                   var firstChild = pElement.firstChild;
                   var astronautsElement = document.createElement("a");
                   var txt = document.createTextNode(res.people[i].name + " ");
                   astronautsElement.appendChild(txt);

                   pElement.insertBefore(astronautsElement, firstChild);
               }
           }
       }

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