Get jquery progress bar value

I want to find the value of the progress bar so that I can increment it by a percentage at each step, but no matter what I tried, either it said it was undefined or the method could not be called before the object was instantiated.

Things I've tried:

 alert($('progressbar:first').prop('progress-label')); 

 progressbarValue = progressbar.find( ".progress-label" ).val();

      

        
        
        
      

    

Html

<div id="progressbar"><div class="progress-label">Form Process</div></div>

      

        
        
        
      

    

if(condition == true) {

    progressbar = $( "#progressbar" );
    progressbarValue = progressbar.find( ".ui-progressbar-value" );
    progressLabel = $( ".progress-label" );


    var size = parseInt($("#fieldWrapper .step").size(),10);
    var progress = 100/size ; 

 alert($('progressbar:first').prop('progress-label')); 
  progressbar.progressbar({
      value: progress,
      change: function() {
        progressLabel.text( progressbar.progressbar( "value" ) + "%" );

      },
      complete: function() {
        progressLabel.text( "Complete!" );
      }
    });

        progressbarValue.css({
          "background": '#' + Math.floor( Math.random() * 16777215 ).toString( 16 )
        });

}