Getting page contents using chrome-remote-interface.js

function getPageContents(url) {
    
    return new Promise((resolve, reject) => {
        CDP((client) => {
            const {Page, Runtime} = client;

            // Evaluate outerHTML after page has loaded
            Page.loadEventFired(() => {
                setTimeout(() => {
                    Runtime.evaluate({expression: 'document.body.outerHTML'}).then((result) => {
                        resolve(result.result.value);
                        client.close();
                    });
                }, 3000);
            });

            // Enable events on domains we are interested in
            Promise.all([
                Page.enable()
            ]).then(() => {
                return Page.navigate({url});
            });

        }).on('error', (err) => {
            console.error('getPageContents: Cannot connect to browser:', err);
            reject();
        });
    });
}