XMLHttpRequest仅在IE中有效

Question

I am using the XMLHttpRequest object for my AJAX calls which has been working fine across browsers with a callback handler I have created to return JSON based on the request type and arguments etc.

But I am now integrating an external RESTful API to return a JSON string and for some reason it only works for me in IE (tested in IE 8). Using fiddler 2 I have determined that the API is returning the correct data.

I get the XMLHttpRequest.readyState of 4 but XMLHttpRequest.status only returns 0 for Chrome, Safari and FF. I read that sometimes when using a local server (test server) you always get a status of zero so I bypassed my check for status but still got a blank string for XMLHttpRequest.responseText.

function ajaxRequest(requestType,url) {

    var xmlhttp;

    if (window.XMLHttpRequest) {
        xmlhttp = new XMLHttpRequest();
    } else {
        xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
    }

    xmlhttp.onreadystatechange = function()
    {

        if (xmlhttp.readyState == 4 && xmlhttp.status == 200)
        {
            switch (requestType)
            {
                case 5:
                    //Home postcode search
                    showAddresses("home", xmlhttp.responseText);
                    break;          
            }
        }
    }
    xmlhttp.open("GET", url, true);
    xmlhttp.send();
}

Answer 1

You should upgrade to jQuery as it will handle this request for nearly all browsers. But if you really want to know how to use XMLHttpRequest across all browsers, here's some code that seems to do the trick: https://github.com/ilinsky/xmlhttprequest/blob/master/XMLHttpRequest.js

Or, just pick apart jQuery's implementation.

http://api.jquery.com/category/ajax/

Hope this helps.

Answer 2

My issue was that I was using an external API and xmlHttpRequest only allows you to makes calls on the same server. I moved my data call into my server code and got the response from my callback handling page instead of going straight out to the API.