在swift 4中如何在WKWebView中删除网页中的DIV标签？

import WebKit

let webView = WKWebView(frame: view.bounds)
view.addSubview(webView)

if let url = URL(string: "https://example.com") {
    let request = URLRequest(url: url)
    webView.load(request)
}

extension ViewController: WKNavigationDelegate {
    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        let script = "var elements = document.getElementsByTagName('div'); for (var i = 0; i < elements.length; i++) { elements[i].parentNode.removeChild(elements[i]); }"
        webView.evaluateJavaScript(script, completionHandler: nil)
    }
}

webView.navigationDelegate = self