229

有没有人有一个更复杂的解决方案/库，用于使用 JavaScript 截断字符串并在末尾添加省略号，而不是显而易见的：

if (string.length > 25) {
  string = string.substring(0, 24) + "...";
}
4

25 回答 25

442

本质上，您检查给定字符串的长度。如果它比给定的长度长n，则将其剪裁为 length n(substr或slice) 并将 html 实体…(...) 添加到剪裁的字符串中。

这样的方法看起来像

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

如果“更复杂”是指在字符串的最后一个单词边界处截断，那么您需要进行额外检查。首先将字符串剪辑到所需的长度，然后将结果剪辑到最后一个单词的边界

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

You can extend the native String prototype with your function. In that case the str parameter should be removed and str within the function should be replaced with this:

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

More dogmatic developers may chide you strongly for that ("Don't modify objects you don't own". I wouldn't mind though).

An approach without extending the String prototype is to create your own helper object, containing the (long) string you provide and the beforementioned method to truncate it. That's what the snippet below does.

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.substr(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>

Finally, you can use css only to truncate long strings in HTML nodes. It gives you less control, but may well be viable solution.

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>

于 2009-07-29T10:56:50.903 回答
71

Note that this only needs to be done for Firefox.

All other browsers support a CSS solution (see support table):

p {
    white-space: nowrap;
    width: 100%;                   /* IE6 needs any width */
    overflow: hidden;              /* "overflow" value must be different from  visible"*/ 
    -o-text-overflow: ellipsis;    /* Opera < 11*/
    text-overflow:    ellipsis;    /* IE, Safari (WebKit), Opera >= 11, FF > 6 */
}

The irony is I got that code snippet from Mozilla MDC.

于 2009-07-29T12:38:15.273 回答
33

There are valid reasons people may wish to do this in JavaScript instead of CSS.

To truncate to 8 characters (including ellipsis) in JavaScript:

short = long.replace(/(.{7})..+/, "$1&hellip;");

or

short = long.replace(/(.{7})..+/, "$1…");
于 2016-10-10T21:50:34.463 回答
31

Use either lodash's truncate 

_.truncate('hi-diddly-ho there, neighborino');
// → 'hi-diddly-ho there, neighbo…'

or underscore.string's truncate.

_('Hello world').truncate(5); => 'Hello...'
于 2016-04-08T13:37:31.313 回答
14 
('long text to be truncated').replace(/(.{250})..+/, "$1…");

Somehow above code was not working for some kind of copy pasted or written text in vuejs app. So I used lodash truncate and its now working fine.

_.truncate('long text to be truncated', { 'length': 250, 'separator': ' '});
于 2019-07-10T15:15:43.910 回答
10

Best function I have found. Credit to text-ellipsis.

function textEllipsis(str, maxLength, { side = "end", ellipsis = "..." } = {}) {
  if (str.length > maxLength) {
    switch (side) {
      case "start":
        return ellipsis + str.slice(-(maxLength - ellipsis.length));
      case "end":
      default:
        return str.slice(0, maxLength - ellipsis.length) + ellipsis;
    }
  }
  return str;
}

Examples:

var short = textEllipsis('a very long text', 10);
console.log(short);
// "a very ..."

var short = textEllipsis('a very long text', 10, { side: 'start' });
console.log(short);
// "...ng text"

var short = textEllipsis('a very long text', 10, { textEllipsis: ' END' });
console.log(short);
// "a very END"
于 2018-05-22T22:41:47.833 回答
8

All modern browsers now support a simple CSS solution for automatically adding an ellipsis if a line of text exceeds the available width:

p {
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

(Note that this requires the width of the element to be limited in some way in order to have any effect.)

Based on https://css-tricks.com/snippets/css/truncate-string-with-ellipsis/.

It should be noted that this approach does not limit based on the number of characters. It also does not work if you need to allow multiple lines of text.

于 2012-03-20T17:42:44.003 回答
7

Here's my solution, which has a few improvements over other suggestions:

String.prototype.truncate = function(){
    var re = this.match(/^.{0,25}[\S]*/);
    var l = re[0].length;
    var re = re[0].replace(/\s$/,'');
    if(l < this.length)
        re = re + "&hellip;";
    return re;
}

// "This is a short string".truncate();
"This is a short string"

// "Thisstringismuchlongerthan25characters".truncate();
"Thisstringismuchlongerthan25characters"

// "This string is much longer than 25 characters and has spaces".truncate();
"This string is much longer&hellip;"

It:

  • Truncates on the first space after 25 characters
  • Extends the JavaScript String object, so it can be used on (and chained to) any string.
  • Will trim the string if truncation results in a trailing space;
  • Will add the unicode hellip entity (ellipsis) if the truncated string is longer than 25 characters
于 2009-07-29T11:37:43.270 回答
6

Most modern Javascript frameworks (JQuery, Prototype, etc...) have a utility function tacked on to String that handles this.

Here's an example in Prototype:

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

This seems like one of those functions you want someone else to deal with/maintain. I'd let the framework handle it, rather than writing more code.

于 2009-07-29T11:27:13.250 回答
4

I like using .slice() The first argument is the starting index and the second is the ending index. Everything in between is what you get back.

var long = "hello there! Good day to ya."
// hello there! Good day to ya.

var short  = long.slice(0, 5)
// hello
于 2019-01-23T20:08:33.077 回答
4

Text-overflow: ellipsis is the property you need. With this and an overflow:hidden with a specific width, everything surpassing that will get the three period effect at the end ... Don't forget to add whitespace:nowrap or the text will be put in multiple lines.

.wrap{
  text-overflow: ellipsis
  white-space: nowrap;
  overflow: hidden;
  width:"your desired width";
}
<p class="wrap">The string to be cut</p>
于 2019-03-26T12:43:20.260 回答
4

I always use the cuttr.js library to truncate strings and add custom ellipsis:

new Cuttr('.container', {
  //options here
  truncate: 'words',
  length: 8,
  ending: '... ►'
});
<script src="https://unpkg.com/cuttr@1.1.1/dist/cuttr.min.js"></script>
<p class="container">Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. </p>

This is bar far the easiest method (and doesn't have any dependencies) I know to cut strings with JS and its also available as jQuery plugin.

于 2020-08-06T18:44:15.427 回答
2

Perhaps I missed an example of where someone is handling nulls, but 3 TOP answers did not work for me when I had nulls ( Sure I realize that error handling is and million other things is NOT the responsibility of the person answering the question, but since I had used an existing function along with one of the excellent truncation ellipsis answers I thought I would provide it for others.

e.g.

javascript: 

news.comments

using truncation function

news.comments.trunc(20, true);

However, on news.comments being null this would "break"

Final 

checkNull(news.comments).trunc(20, true)

trunc function courtesy of KooiInc

String.prototype.trunc =
 function (n, useWordBoundary) {
     console.log(this);
     var isTooLong = this.length > n,
         s_ = isTooLong ? this.substr(0, n - 1) : this;
     s_ = (useWordBoundary && isTooLong) ? s_.substr(0, s_.lastIndexOf(' ')) : s_;
     return isTooLong ? s_ + '&hellip;' : s_;
 };

My simple null checker (checks for literal "null" thing too (this catches undefined, "", null, "null", etc..)

  function checkNull(val) {
      if (val) {
          if (val === "null") {
              return "";
          } else {
              return val;
          }
      } else {
          return "";
      }
  }
于 2015-12-07T17:31:44.740 回答
2

Sometimes file names are numbered, where the index may be at the beginning or the end. So I wanted to shorten from the center of the string:

function stringTruncateFromCenter(str, maxLength) {
    const midChar = "…";      // character to insert into the center of the result
    var left, right;

    if (str.length <= maxLength) return str;

    // length of beginning part      
    left = Math.ceil(maxLength / 2);

    // start index of ending part   
    right = str.length - Math.floor(maxLength / 2) + 1;   

    return str.substr(0, left) + midChar + str.substring(right);
}

Be aware that I used a fill character here with more than 1 byte in UTF-8.

于 2018-01-31T16:40:10.163 回答
1

通过快速谷歌搜索，我发现了这个......这对你有用吗？

/**
 * Truncate a string to the given length, breaking at word boundaries and adding an elipsis
 * @param string str String to be truncated
 * @param integer limit Max length of the string
 * @return string
 */
var truncate = function (str, limit) {
    var bits, i;
    if (STR !== typeof str) {
        return '';
    }
    bits = str.split('');
    if (bits.length > limit) {
        for (i = bits.length - 1; i > -1; --i) {
            if (i > limit) {
                bits.length = i;
            }
            else if (' ' === bits[i]) {
                bits.length = i;
                break;
            }
        }
        bits.push('...');
    }
    return bits.join('');
};
// END: truncate
于 2009-07-29T10:48:46.837 回答
1

You can use the Ext.util.Format.ellipsis function if you are using Ext.js.

于 2012-07-30T19:50:34.087 回答
1

I upvoted Kooilnc's solution. Really nice compact solution. There's one small edge case that I would like to address. If someone enters a really long character sequence for whatever reason, it won't get truncated:

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 + '&hellip;' : str;
}
于 2013-12-11T15:24:11.257 回答
0

c_harm's answer is in my opinion the best. Please note that if you want to use 

"My string".truncate(n)

you will have to use a regexp object constructor rather than a literal. Also you'll have to escape the \S when converting it.

String.prototype.truncate =
    function(n){
        var p  = new RegExp("^.{0," + n + "}[\\S]*", 'g');
        var re = this.match(p);
        var l  = re[0].length;
        var re = re[0].replace(/\s$/,'');

        if (l < this.length) return re + '&hellip;';
    };
于 2013-02-27T09:11:22.397 回答
0

Use following code

 function trancateTitle (title) {
    var length = 10;
    if (title.length > length) {
       title = title.substring(0, length)+'...';
    }
    return title;
}
于 2014-04-23T14:01:47.753 回答
0

Correcting Kooilnc's solution:

String.prototype.trunc = String.prototype.trunc ||
  function(n){
      return this.length>n ? this.substr(0,n-1)+'&hellip;' : this.toString();
  };

This returns the string value instead of the String object if it doesn't need to be truncated.

于 2014-11-19T00:12:10.843 回答
0

I recently had to do this and ended up with:

/**
 * Truncate a string over a given length and add ellipsis if necessary
 * @param {string} str - string to be truncated
 * @param {integer} limit - max length of the string before truncating
 * @return {string} truncated string
 */
function truncate(str, limit) {
    return (str.length < limit) ? str : str.substring(0, limit).replace(/\w{3}$/gi, '...');
}

Feels nice and clean to me :)

于 2017-01-31T15:26:25.947 回答
0

Somewhere Smart :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))

于 2019-02-22T07:41:42.123 回答
0

Here are my solutions with word boundary.

let s = "At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."
let s_split = s.split(/\s+/);
let word_count = 0;
let result = "";
//1
for(let i = 0; word_count < 100; i++){
  word_count += s_split[i].length+1;
  result += (s_split[i] + " ");
}
console.log(result);
// 2
word_count = 0;
result = s_split.reduce((x,y)=>{
  word_count+=(y.length+1);
  if(word_count>=100) return x;
  else return x+" "+y;}, "").substring(1);
console.log(result);

于 2020-12-03T16:34:40.743 回答
0

If you want to do it with css instead of JavaScript;

.textShortDesc { /*Here we have determined the max number of lines.*/
    display: block; /* or inline-block */
    -o-text-overflow: ellipsis; /* Opera < 11*/
    text-overflow: ellipsis; /* IE, Safari (WebKit), Opera >= 11, FF > 6 */
    word-wrap: break-word;
    overflow: hidden;
    max-height: 2em; /*max-height/line-height=rowCount */
    line-height: 1em;
}
于 2021-04-30T03:11:30.953 回答
-1

This function do the truncate space and words parts also.(ex: Mother into Moth...)

String.prototype.truc= function (length) {
        return this.length>length ? this.substring(0, length) + '&hellip;' : this;
};

usage:

"this is long length text".trunc(10);
"1234567890".trunc(5);

output:

this is lo...

12345...

于 2017-09-27T11:37:18.593 回答