Question

我对xmlhttp对象不太熟悉，尽管有可用的文档，但我无法获得responseText。我是如此接近，但会感谢任何能指出为什么以下不起作用的人;在send()它刚刚死后......：

function fetchgenotype() {
    // here's where we use an Ajax function to fetch the allele values without reloading the page.
    // Get the index number of the genotype record to retrieve; retrieve it; populate the alleles.
    var mndx, sndx = 0;
    mndx = $('#marker').val();
    if (Study_selected) {
        sndx = $('#stylabid').val();
    } else {
        sndx = $('#pjtlabid').val();
    }
    if (window.XMLHttpRequest) {
        // code for IE7+, Firefox, Chrome, Opera, Safari
        xmlhttp = new XMLHttpRequest();
    } else {
        // code for IE6, IE5
        xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
    }
    xmlhttp.onreadystatechange = function () {
        if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
            // Recieve the return value, parse and assign to screen form. 
            var allele_stg = "";
            allele_stg = document.getElementById("allele_ary").innerHTML = xmlhttp.responseText;
            ary = new Array();
            ary = str_getcsv(allele_ary, ',');
            $('#allele_1_1').val() = ary[0];
            $('#allele_1_2').val() = ary[1];
        }
    }
    xmlhttp.open("GET", "fetchAlleles.php?mndx=" + mndx + "&sndx=" + sndx, true);
    xmlhttp.send();
} // end of fetchgenotype

Answer 1

您可以通过将if语句更改为：

来查看实际获得的结果

if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
    // Receive the return value, parse and assign to screen form. 
    var allele_stg = "",
        rText = xmlhttp.responseText;
    /*
     * By assigning xmlhttp.responseText to a seperate variable
     * you can now check to make sure rText contains what you
     * expect to see.
     * 
     * By making the call to getElementById and assigning the
     * innerHTML property in separate statements, you can now
     * check to make sure that getElementById is returning a
     * DOM element, or if it's undefined.
     */
    allele_stg = document.getElementById("allele_ary");
    allele_stg.innerHTML = rText;
    ary = new Array();
    ary = str_getcsv(allele_ary, ',');
    $('#allele_1_1').val() = ary[0];
    $('#allele_1_2').val() = ary[1];
} else {
    console.log('xmlhttp.readyState:' + xmlhttp.readyState);
    console.log('xmlhttp.status:' + xmlhttp.status);
}

然后监控控制台。我怀疑你要么没有200 xmlhttp.status，要么xmlhttp.readyState从未到达4。

我如何获得XMLhttp responseText？

1 个答案: