How do I write content to another browser window using Javascript?

var myWindow = window.open('...')
myWindow.document.getElementById('foo').style.backgroundColor = 'red'

function popUp(){

    var newWindow = window.open("","Test","width=300,height=300,scrollbars=1,resizable=1")

    //read text from textbox placed in parent window
    var text = document.form.input.value

    var html = "<html><head></head><body>Hello, <b>"+ text +"</b>."
    html += "How are you today?</body></html>"


    newWindow .document.open()
    newWindow .document.write(html)
    newWindow .document.close()

    }