Copy files based on a custom column value between document libraries in sharepoint using javascript

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Javascript

SharePoint

I am new to Javascript and currently working on a task where I need to copy files based on a custom column name "PID" which is a lookup column from One Document Library to the other.

I was able to get the below code to work which copies all the files

$scope.copyFiles=function()
{

var sourceLib = '/sites/Protocol/ProtocolDocument';
var destLib = '/sites/Protocol/FinalProtocolDocuments';


var context = new SP.ClientContext.get_current();
var web = context.get_web().get_lists();
var folderSrc = web.getFolderByServerRelativeUrl(sourceLib);
//var cq = "<Query><Where><Eq><FieldRef Name="ProtocolID" LookupId="TRUE"/><Value Type="Text">' + 466 + '</Value></Eq></Where></Query>"
context.load(folderSrc,'Files');
context.executeQueryAsync(
function() {

           console.log("Got the source folder right here!");
           var files = folderSrc.get_files();
           var e = files.getEnumerator();
           var dest = [];
           while (e.moveNext()) {
           var file = e.get_current();
           var destLibUrl = destLib + "/" + file.get_name();
           dest.push(destLibUrl); //delete this when we're happy we got the file paths right
           file.copyTo(destLibUrl, true);

           }

        console.log(dest); //delete this when we're happy we got the file paths right
        context.executeQueryAsync(function() { console.log("Files moved successfully!");}, function(sender, args) {console.log("error: ") + args.get_message()});
        }, 
    function(sender, args){console.log("Sorry, something messed up: " + args.get_message());}
    );   

   }

What I have tried:

I did some research online to get the Filenames based on a custom column value with no luck

Also tried to use CAML , however not sure how to use it in the code.

Would appreciate if anyone could help me get the filenames from a Document Library based on custom column name "PID" so that only selected/filtered files are moved to the destination Library