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>"

逻辑如下

得到字符串的长度 如果大于阈值，则获取 子字符串并以省略号或其他符号结束 否则，返回输入字符串 函数truncateString(str: string, num: number, end: string = '…'){ 返回str.length > num ?str.slice(0, num) + end: str; ｝

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('');
    }

如果您想通过Limit(符号)截断， 但对于不长的文本(例如标题)，你不想删减单词(保留最后一个单词完整):

trancWord(str, limit) {
    str = str.split(' ');
    let summ = 0
    for (let [index, value]  of str.entries()) {
        summ  += value.length
        if (summ > limit) {
            let cutTolimit = str.slice(0, index);
            return str.slice(0, index).join(' ') + ' ' + '...';
        }
    }
    return str.join(' ');
}

对于长字符串(一些长文本后Vue-3使用过滤器):

trancWord  (str, max){
        if (str.length <= max) { return str; }
        let subString = str.substr(0, max);
        return (str ? subString.substr(0, subString.lastIndexOf(' ')) : subString) + '...';
}

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);