Why does my browser still show the loading icon after I clicked the button?

Why does my browser still show the loading icon after I clicked the button?

jsfiddle.net/QuwUF/1

<script type="text/javascript">
    f开发者_如何学编程unction printName(name){
        var message= document.write("hi " + name);
        return message;
    }
</script>


<form>
    <input type="button" onclick='printName("scotty")' />

</form>

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You (implicitly — by calling document.write() on a closed document) open a new document, but after you write to it, you never call document.close() so it never finishes "loading".