从ajax运行javascript

Question

I use the following function to make an ajax call to a PHP that retrieves data from a MySQL database whenever an onChange-Event occurs. The result of the PHP is a JavaScript function including some data.

Basically, I copied all the code down to xmlhttp.send() from W3Schools. Then, facing the problem of calling the JavaScript on my page, I added the part with $.getScript(...).

It works, but I have a feeling that calling getRun.php?run=... twice cannot be the best way.

function getRun(str) {
if (str == "") {
    document.getElementById("txtHint").innerHTML = "";
    return;
} else { 
    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 (this.readyState == 4 && this.status == 200) {
            document.getElementById("txtHint").innerHTML = this.responseText;
        } 
    };
    xmlhttp.open("GET","getRun.php?run="+str,true);
    xmlhttp.send();
    $.getScript("getRun.php?run="+str, function() {
        setTimeout();
    });
}

}

Do you have any hints on what would be a better way?

Answer 1

To further explain my comment on your question:

1. Define the function you want to run from your Ajax result
2. Launch your Ajax request to your PHP backend.
3. The PHP backend returns a certain result, be it a string or some JSON, up to you.
4. Call the function in the Ajax success (or error, or complete even) callback.

E.g.

function getDataFromBackend(){

    // Your Ajax request
    // Seeing as you tried to use $.getScript, you might be using jQuery, so an example with jQuery
    $.ajax({
        method: 'POST',
        url: 'yoururl.php',
        data: {}, // You can put whatever data you wanna send in this object
        success: runMeWithData // The success callback runs the function when the Ajax request comes back without errors.
    });

}

function runMeWithData(dataFromAjax){
    console.log(dataFromAjax); // Show the output of your backend in the Console
}