ES6更新版本

const truncateString = (string = "， maxLength = 50) => 字符串。length > maxLength ？ “${字符串。substring(0,最大长度)}……” :字符串 //演示上述函数 alert(truncateString('Hello World'， 4));

下面的代码截断字符串，不拆分单词，而是丢弃发生截断的单词。完全基于Sugar.js源代码。

function truncateOnWord(str, limit) {
        var trimmable = '\u0009\u000A\u000B\u000C\u000D\u0020\u00A0\u1680\u180E\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200A\u202F\u205F\u2028\u2029\u3000\uFEFF';
        var reg = new RegExp('(?=[' + trimmable + '])');
        var words = str.split(reg);
        var count = 0;
        return words.filter(function(word) {
            count += word.length;
            return count <= limit;
        }).join('');
    }

以防你想按单词截断。

function limit(str, limit, end) { limit = (limit)? limit : 100; end = (end)? end : '...'; str = str.split(' '); if (str.length > limit) { var cutTolimit = str.slice(0, limit); return cutTolimit.join(' ') + ' ' + end; } return str.join(' '); } var limit = limit('ILorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus metus magna, maximus a dictum et, hendrerit ac ligula. Vestibulum massa sapien, venenatis et massa vel, commodo elementum turpis. Nullam cursus, enim in semper luctus, odio turpis dictum lectus', 20); console.log(limit);

使用substring方法:

var length = 3;
var myString = "ABCDEFG";
var myTruncatedString = myString.substring(0,length);
// The value of myTruncatedString is "ABC"

在你的例子中:

var length = 3;  // set to the number of characters you want to keep
var pathname = document.referrer;
var trimmedPathname = pathname.substring(0, Math.min(length,pathname.length));

document.getElementById("foo").innerHTML =
     "<a href='" + pathname +"'>" + trimmedPathname + "</a>"

var str = "Anything you type in.";
str.substring(0, 5) + "" //you can type any amount of length you want

是的，substring工作得很好:

stringTruncate('Hello world', 5); //output "Hello..."
stringTruncate('Hello world', 20);//output "Hello world"

var stringTruncate = function(str, length){
  var dots = str.length > length ? '...' : '';
  return str.substring(0, length)+dots;
};