修剪字符串宽度jQuery[重复]

var text = $('.streetname').text();
var newText = text.substr(0,17) + '...';
$('.streetname').text(newText)

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<p class="streetname">Galloway Road, Bishop's Stortford</p>

if ($(".streetname").text().length > 20) {         
    $(".streetname").text($(".streetname").text().substring(0,50) + '...');
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<p class="streetname">This text is way to long to be displayed on the site so we just short it with jquery</p>