使用循環的Ajax請求

Question

你能幫我請把ajax code整合到for循環中嗎？

我想從具有類「鏈接」的元素獲取href，然後使用它們製作httpRequests。
我已經看到與螢火蟲，httpRequests發送，我認爲問題是在alertContents函數somwere。 我一整天都在掙扎，但沒有結果。

<a class="links" href="/1">Link1</a> 
<a class="links" href="/2">Link2</a> 
<a class="links" href="/3">Link3</a> 

<script> 
for(var i = 0; i < 2; i++) { 
makeRequest(document.getElementsByClassName("links")[i].href); 
} 

function makeRequest(url) { 
if (window.XMLHttpRequest) { // Mozilla, Safari, ... 
    httpRequest = new XMLHttpRequest(); 
} else if (window.ActiveXObject) { // IE 
    try { 
    httpRequest = new ActiveXObject("Msxml2.XMLHTTP"); 
    } 
    catch (e) { 
    try { 
     httpRequest = new ActiveXObject("Microsoft.XMLHTTP"); 
    } 
    catch (e) {} 
    } 
} 

if (!httpRequest) { 
    alert('Giving up :(Cannot create an XMLHTTP instance'); 
    return false; 
} 
httpRequest.onreadystatechange = alertContents; 
httpRequest.open('GET', url); 
httpRequest.send(); 
} 

function alertContents() { 
if (httpRequest.readyState === 4) { 
    if (httpRequest.status === 200) { 
    alert(httpRequest.responseText); 
    // here i get the final value of the variable i 
    } else { 
    alert('There was a problem with the request.'); 
    } 
} 
} 
</script> 

Answer 1

我聲明瞭變量，因此它不是全局變量，並將您的回調函數移動到了makeRequest函數中。

for (var i = 0; i < 2; i++) { 
    makeRequest(document.getElementsByClassName("links")[i].href); 
} 

function makeRequest(url) { 

    var httpRequest; 

    function alertContents() { 
     if (httpRequest.readyState === 4) { 
      if (httpRequest.status === 200) { 
       alert(httpRequest.responseText); 
       // here i get the final value of the variable i 
      } else { 
       alert('There was a problem with the request.'); 
      } 
     } 
    } 

    if (window.XMLHttpRequest) { // Mozilla, Safari, ... 
     httpRequest = new XMLHttpRequest(); 
    } else if (window.ActiveXObject) { // IE 
     try { 
      httpRequest = new ActiveXObject("Msxml2.XMLHTTP"); 
     } catch (e) { 
      try { 
       httpRequest = new ActiveXObject("Microsoft.XMLHTTP"); 
      } catch (e) {} 
     } 
    } 

    if (!httpRequest) { 
     alert('Giving up :(Cannot create an XMLHTTP instance'); 
     return false; 
    } 
    httpRequest.onreadystatechange = alertContents; 
    httpRequest.open('GET', url); 
    httpRequest.send(); 

}