我对Kooilnc的解决方案投了赞成票。非常好的紧凑解决方案。有一个小的边缘情况，我想解决。如果有人出于某种原因输入了一个很长的字符序列，它不会被截断:

function truncate(str, n, useWordBoundary) {
    var singular, tooLong = str.length > n;
    useWordBoundary = useWordBoundary || true;

    // Edge case where someone enters a ridiculously long string.
    str = tooLong ? str.substr(0, n-1) : str;

    singular = (str.search(/\s/) === -1) ? true : false;
    if(!singular) {
      str = useWordBoundary && tooLong ? str.substr(0, str.lastIndexOf(' ')) : str;
    }

    return  tooLong ? str + '…' : str;
}

聪明的地方:D

//My Huge Huge String let tooHugeToHandle = `It is a long established fact that a reader will be distracted by the readable content of a page when looking at its layout. The point of using Lorem Ipsum is that it has a more-or-less normal distribution of letters, as opposed to using 'Content here, content here', making it look like readable English. Many desktop publishing packages and web page editors now use Lorem Ipsum as their default model text, and a search for 'lorem ipsum' will uncover many web sites still in their infancy. Various versions have evolved over the years, sometimes by accident, sometimes on purpose (injected humour and the like).` //Trim Max Length const maxValue = 50 // The barber. const TrimMyString = (string, maxLength, start = 0) => { //Note - `start` is if I want to start after some point of the string if (string.length > maxLength) { let trimmedString = string.substr(start, maxLength) return ( trimmedString.substr( start, Math.min(trimmedString.length, trimmedString.lastIndexOf(' ')) ) + ' ...' ) } return string } console.log(TrimMyString(tooHugeToHandle, maxValue))

('long text to be truncated').replace(/(.{250})..+/, "$1…");

不知何故，上面的代码是不工作的某种复制粘贴或书面文本在vuejs应用程序。所以我使用lodash截断，它现在工作正常。

_.truncate('long text to be truncated', { 'length': 250, 'separator': ' '});

大多数现代Javascript框架(JQuery, Prototype等)都有一个附加在String上的实用函数来处理这个问题。

下面是Prototype中的一个例子:

'Some random text'.truncate(10);
// -> 'Some ra...'

这似乎是您希望其他人处理/维护的功能之一。我会让框架来处理它，而不是编写更多的代码。

本质上，检查给定字符串的长度。如果它比给定的长度n长，剪辑到长度n (substr或slice)，并添加html实体…(…)到剪短的字符串。

这样的方法看起来像

function truncate(str, n){
  return (str.length > n) ? str.slice(0, n-1) + '…' : str;
};

如果你所说的“更复杂”是指在字符串的最后一个单词边界处截断，那么你需要额外的检查。 首先将字符串剪辑到所需的长度，然后将其结果剪辑到最后一个单词边界

function truncate( str, n, useWordBoundary ){
  if (str.length <= n) { return str; }
  const subString = str.slice(0, n-1); // the original check
  return (useWordBoundary 
    ? subString.slice(0, subString.lastIndexOf(" ")) 
    : subString) + "&hellip;";
};

您可以用您的函数扩展本机String原型。在这种情况下，str形参应该被删除，函数中的str应该被替换为:

String.prototype.truncate = String.prototype.truncate || 
function ( n, useWordBoundary ){
  if (this.length <= n) { return this; }
  const subString = this.slice(0, n-1); // the original check
  return (useWordBoundary 
    ? subString.slice(0, subString.lastIndexOf(" ")) 
    : subString) + "&hellip;";
};

更教条的开发人员可能会因此强烈地责备你(“不要修改你不拥有的对象”)。不过我不介意)。

一种不扩展String原型的方法是创建 您自己的helper对象，包含您提供的(长)字符串 和前面提到的截断方法。这就是代码片段 下面。

const LongstringHelper = str => { const sliceBoundary = str => str.substr(0, str.lastIndexOf(" ")); const truncate = (n, useWordBoundary) => str.length <= n ? str : `${ useWordBoundary ? sliceBoundary(str.slice(0, n - 1)) : str.slice(0, n - 1)}&hellip;`; return { full: str, truncate }; }; const longStr = LongstringHelper(`Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum`); const plain = document.querySelector("#resultTruncatedPlain"); const lastWord = document.querySelector("#resultTruncatedBoundary"); plain.innerHTML = longStr.truncate(+plain.dataset.truncateat, !!+plain.dataset.onword); lastWord.innerHTML = longStr.truncate(+lastWord.dataset.truncateat, !!+lastWord.dataset.onword); document.querySelector("#resultFull").innerHTML = longStr.full; body { font: normal 12px/15px verdana, arial; } p { width: 450px; } #resultTruncatedPlain:before { content: 'Truncated (plain) n='attr(data-truncateat)': '; color: green; } #resultTruncatedBoundary:before { content: 'Truncated (last whole word) n='attr(data-truncateat)': '; color: green; } #resultFull:before { content: 'Full: '; color: green; } <p id="resultTruncatedPlain" data-truncateat="120" data-onword="0"></p> <p id="resultTruncatedBoundary" data-truncateat="120" data-onword="1"></p> <p id="resultFull"></p>

最后，您可以使用css仅截断HTML节点中的长字符串。它给你较少的控制，但可能是可行的解决方案。

body { font: normal 12px/15px verdana, arial; margin: 2rem; } .truncate { white-space: nowrap; overflow: hidden; text-overflow: ellipsis; width: 30vw; } .truncate:before{ content: attr(data-longstring); } .truncate:hover::before { content: attr(data-longstring); width: auto; height: auto; overflow: initial; text-overflow: initial; white-space: initial; background-color: white; display: inline-block; } <div class="truncate" data-longstring="Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."></div>

我对Kooilnc的解决方案投了赞成票。非常好的紧凑解决方案。有一个小的边缘情况，我想解决。如果有人出于某种原因输入了一个很长的字符序列，它不会被截断:

function truncate(str, n, useWordBoundary) {
    var singular, tooLong = str.length > n;
    useWordBoundary = useWordBoundary || true;

    // Edge case where someone enters a ridiculously long string.
    str = tooLong ? str.substr(0, n-1) : str;

    singular = (str.search(/\s/) === -1) ? true : false;
    if(!singular) {
      str = useWordBoundary && tooLong ? str.substr(0, str.lastIndexOf(' ')) : str;
    }

    return  tooLong ? str + '…' : str;
}