JavaScript IF / ELSE to call another JS Script?

Question

I need to call one of two Java scripts depending on the condition, for example:

<script type="text/javascript">
if(b_condition)
  <script type="text/javascript" src="http://script1.js"></script>
else
  <script type="text/javascript" src="http://script2.js"></script>
</script>

But that does not work. Any ideas how to call another javascript call in an If / Else block?

Answer 1

What the hell? Why is everyone here advocating document.write ()? Sure enough that we moved on to this as standard practice at this point; document.write is not even valid if you are in XHTML customization.

The best way to do this would be as follows (also here, for better highlighting / parsing: https://gist.github.com/767131 ):

/*  Since script loading is dynamic/async, we take
    a callback function with our loadScript call
    that executes once the script is done downloading/parsing
    on the page.
*/
var loadScript = function(src, callbackfn) {
    var newScript = document.createElement("script");
    newScript.type = "text/javascript";
    newScript.setAttribute("async", "true");
    newScript.setAttribute("src", src);

    if(newScript.readyState) {
        newScript.onreadystatechange = function() {
            if(/loaded|complete/.test(newScript.readyState)) callbackfn();
        }
    } else {
        newScript.addEventListener("load", callbackfn, false);
    }

    document.documentElement.firstChild.appendChild(newScript);
}

if(a) {
    loadScript("lulz.js", function() { ... });
} else {
    loadScript("other_lulz.js", function() { ... });
}

jQuery , loadScript (ala $.getScript ..).

Answer 2

- :

var file=document.createElement('script')
file.setAttribute("type","text/javascript")
file.setAttribute("src", "script1.js")

, :

document.getElementsByTagName("head")[0].appendChild(file)

Answer 3

, :

<script type="text/javascript">
if(b_condition)
  document.write('<scri'+'pt src="http://script1.js"></'+'script>');
else
  document.write('<scri'+'pt src="http://scripts2.js"></'+'script>');
</script>

, document.write , . ? - .

Answer 4

/ , , - :

<script type="text/javascript" src="http://script1+2.js"></script>
<script type="text/javascript">
    if(b_condition) {
        functionA();
    } 
    else {
        functionB();
    }
</script>

Answer 5

script , script DOM . http://ajaxpatterns.org/On-Demand_Javascript

Answer 6

script1.js script2.js ?

, , , .

Answer 7

, , , . , javascript, , .

If there is no other way than you can do it this way:

<script type="text/javascript">
    var script = document.createElement('script');
    if((b_condition){
        script.src = 'script1.js';
    }else{
        script.src = 'script1.js';
    }
    document.body.appendChild(script);
</script>

Answer 8

   <script type="text/javascript">     
    if(condition==true)
    {
        var src = "js/testing_true.js";
        var newScript = document.createElement("script");
        newScript.type = "text/javascript";
        newScript.setAttribute("async", "true");
        newScript.setAttribute("src", src);
        document.body.appendChild(newScript);
    }else
    {

        var src = "js/testing_false.js";
        var newScript = document.createElement("script");
        newScript.type = "text/javascript";
        newScript.setAttribute("async", "true");
        newScript.setAttribute("src", src);
        document.body.appendChild(newScript);
    }
</script>

Answer 9

<script type="text/javascript">
   if(b_condition)
      document.write('<script type="text/javascript" src="http://script1.js"></script>');
   else
      document.write('<script type="text/javascript" src="http://script2.js"></script>');
</script>

Answer 10

<?php if (a_condition) {?>
put html code here or script or whatever you like
<?php } elseif(b_condition) {?>
put any other code here 
<?php } else {?>
put even more code
<?php } ?>