Using jQuery / javascript How to check if JS file ( SP.JS) is already called in a page?

Question

I want to check if a particular JS file is already loaded in document.ready.

Something like this:

if(file already called/loaded) { // my code }
else {//some other code}

The JS File is not any plugin.

Its basically a JS file related to SharePoint like Sp.JS.

We just know the file name.

[Update - Added the code ]

I have added the below code and it throws an error in console : SP.Runtime.js is already loaded.

If I remove the loading of SP.Runtime.js my code doesnt work in some pages where Runtime.Js is not loaded by default.

$(document).ready(function() {
    var scriptbase = _spPageContextInfo.webServerRelativeUrl + "/_layouts/15/";
    $.getScript(scriptbase + "init.js",
    function() {
        $.getScript(scriptbase + "SP.Runtime.js",
        function() {
            $.getScript(scriptbase + "SP.js",
            function() {
                    $.getScript(scriptbase + "SP.Taxonomy.js",
                    function() {
                        context = SP.ClientContext.get_current();
                       // My custom function //

                    });
            });
    });
    });
});

Please suggest.

Thanks

Answer 1

SharePoint JavaScript Library, in particular SP.SOD namespace contains methods for loading/ensuring JavaScript files.

1. SP.SOD.executeOrDelayUntilScriptLoaded - executes the specified function if the file containing it is loaded, for example:

   ExecuteOrDelayUntilScriptLoaded(myfunc, "SP.js");
   
   function myfunc()
   {
   }
   

   In that case myfunc will be invoked after sp.js file is loaded

2. SP.SOD.executeFunc - ensures that the specified file that contains the specified function is loaded and then runs the specified callback function, for example:

   SP.SOD.executeFunc('sp.js', 'SP.ClientContext', 
    function (){
        //your code goes here...
    });
   

   The behavior is similar to previous example but the main difference that this function also supports load on demand scripts.