Serverside paywall vs clientside paywall js snippet

paywallDetector.js

function checkPaywall() {
    let structured = JSON.parse(document.querySelector("script[type*='ld+json']").innerText);
	let hasPart = null;
    if(structured.hasPart) {
      hasPart = structured.hasPart;
    }
	else if(structured.length) {
	  for(var  i = 0; i < structured.length; i++) {
	     if(structured[i].hasPart) {
		    hasPart = structured[i].hasPart;
			break;
		 }
       }
	}
	if(!hasPart) {
		window.alert("Doesn't seem paywalled?");
		return;
	}
  let paywallCss = null;
  if(hasPart.cssSelector) {
	   paywallCss = hasPart.cssSelector;
  }
  else if(hasPart.length) {
    for(var i = 0; i < hasPart.length; i++) {
	     if(hasPart[i].cssSelector) {
		    paywallCss = hasPart[i].cssSelector;
			  break;
       }
		 }
  }
	if(!paywallCss) {
		window.alert("Content not paywalled");
		return;
	}
	let e = document.querySelector(paywallCss);
	if(!e) {
		window.alert("Server-Side Paywall");
		return;
	}
	let text = e.innerText;
	if(text.length<300) {
		window.alert("Server-Side Paywall");
		return;
	}
	window.alert("Client-Side Paywall");
}
checkPaywall();