JavaScript reading visualforce binded variables

Question

I need some help understand how JavaScript and Visualforce interact.

I have a eventListener that works perfectly when the DOM is loaded:

window.addEventListener('DOMContentLoaded', function() {
if ('{!bvs.Status__c}' != 'Completed') {
    document.getElementById("populatedChart").style.display = "none";
}
if ('{!bvs.Status__c}' == 'Completed') {
    document.getElementById("oldPullreportbutton").style.display = "none";
}
if ('{!bvs.CompanyName__c}'.length > 0) {
    document.getElementById("blankComp").style.fontWeight="bold"; 
}
});    

I also have some code that tells the div to reRender after a button click:

<apex:commandLink action="{!pullReport}" onclick="showCreditPull()" oncomplete="stopSpinner()" value="Pull Report"/>

function showCreditPull() {
    var panel = $('.spinBorder');
    var spinner = panel.find(".business-loading-icon");
    spinner.show();
}

function stopSpinner(){
  var panel = $('.spinBorder');
  var spinner = panel.find(".business-loading-icon");
  spinner.hide();  
  rerenderData();//this is an actionFunction that reRenders the div
  if ('{!bvs.Status__c}' != null){
      document.getElementById("oldPullreportbutton").style.display = "none";
  }
  else{
      $("#populatedChart").replaceWith( "<p>Error!</p>" ); 
  }
}

My question is- why does is {!bvs.Status__c} in stopSpinner() not recognized? No matter what the status is, it runs through and hides the oldPullreportbutton. It's acting like it doesn't recognize the binded {!bvs.Status__c}. But it is able to be read with the eventListener.

UPDATE: Code from inspect:

if(true){
    document.getElementById("oldPullreportbutton").style.display = "none";
    $("#populatedChart").replaceWith( "<p>Error!</p>" );
    console.log('got out 1');
}

Answer 1

'{!bvs.Status__c}' is guaranteed to never be null, because even if Status is an empty string, your code effectively evaluates as:

if('' != null) {

Clearly, "empty string" is not the same as null, so this condition is always true.

Instead, consider using:

if({!ISBLANK(bvs.Status__c)}) {

Which will evaluate to this when the string is empty:

if(true) {

And will evaluate to this otherwise:

if(false) {