how to use cordova plugin in ionic 4 code example

Example: Cordova Plugin InAppBrowser sample

var inAppBrowserRef;

function showHelp(url) {

    var target = "_blank";

    var options = "location=yes,hidden=yes,beforeload=yes";

    inAppBrowserRef = cordova.InAppBrowser.open(url, target, options);

    inAppBrowserRef.addEventListener('loadstart', loadStartCallBack);

    inAppBrowserRef.addEventListener('loadstop', loadStopCallBack);

    inAppBrowserRef.addEventListener('loaderror', loadErrorCallBack);

    inAppBrowserRef.addEventListener('beforeload', beforeloadCallBack);

    inAppBrowserRef.addEventListener('message', messageCallBack);
}

function loadStartCallBack() {

    $('#status-message').text("loading please wait ...");

}

function loadStopCallBack() {

    if (inAppBrowserRef != undefined) {

        inAppBrowserRef.insertCSS({ code: "body{font-size: 25px;}" });

        inAppBrowserRef.executeScript({ code: "\
            var message = 'this is the message';\
            var messageObj = {my_message: message};\
            var stringifiedMessageObj = JSON.stringify(messageObj);\
            webkit.messageHandlers.cordova_iab.postMessage(stringifiedMessageObj);"
        });

        $('#status-message').text("");

        inAppBrowserRef.show();
    }

}

function loadErrorCallBack(params) {

    $('#status-message').text("");

    var scriptErrorMesssage =
       "alert('Sorry we cannot open that page. Message from the server is : "
       + params.message + "');"

    inAppBrowserRef.executeScript({ code: scriptErrorMesssage }, executeScriptCallBack);

    inAppBrowserRef.close();

    inAppBrowserRef = undefined;

}

function executeScriptCallBack(params) {

    if (params[0] == null) {

        $('#status-message').text(
           "Sorry we couldn't open that page. Message from the server is : '"
           + params.message + "'");
    }

}

function beforeloadCallBack(params, callback) {

    if (params.url.startsWith("http://www.example.com/")) {

        // Load this URL in the inAppBrowser.
        callback(params.url);
    } else {

        // The callback is not invoked, so the page will not be loaded.
        $('#status-message').text("This browser only opens pages on http://www.example.com/");
    }

}

function messageCallBack(params){
    $('#status-message').text("message received: "+params.data.my_message);
}