blocks|key|3987737|text|您可以采用的一种方法是将字符串拆分为数组中的字符。从位置250到位置0遍历数组，并在找到一个点时中断。获取点索引，并将原始数组从起始字符0拼接到该点的索引值加上1的点，因为拼接不包括最后一个值。然后再次将该数组转换为字符串。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3987738|let+string+=+"Lorem+ipsum+dolor+sit+amet,+consectetur+adipiscing+elit.+Sed+in+neque.+Vivamus+tellus.+Donec+magna.+Donec+consequat+hendrerit+magna.+In+iaculis+neque+eget+nisi.+Maecenas+vehicula,+leo+eu+commodo+aliquam,+sem+dolor+iaculis+eros,+vel+mollis+sem+urna+ac+sapien.+Integer+mattis+dui+ut+erat.+Phasellus+nibh+magna,+tempor+vitae,+dictum+sed,+vehicula+sed,+mauris.+In+enim+arcu,+porta+vel,+dictum+eu,+pretium+a,+ipsum.+Donec+cursus,+lorem+ac+posuere+viverra,+sem+tellus+accumsan+dolor,+vel+accumsan+tortor+est+et+est.";

let+arrarOfChar+=+string.split("");+//turns+string+into+array
let+position+=+-1;+//-1+indicates+that+no+dot+has+been+found
for(let+i+=+250+;+i+>=+0+;+i--)+{+//loop+from+250+to+0
++++if(arrarOfChar[i]+==+".")+{+//if+that+char+is+equal+to+"."
++++position+=+i;+//set+the+position+value+to+that
++++break;+//break+the+for+loop
++}
}
if(position+>+0)+{+//only+if+we+found+a+dot
++let+newShortArrayOfChar+=+arrarOfChar.slice(0,position%2B1);+//shorten+the+array+from+0+to+the+dot+index
++let+finalString+=+"";+//this+is+the+final+string
++for(let+i+=+0;+i+<+newShortArrayOfChar.length+;+i%2B%2B)+{
++++finalString+%2B=+newShortArrayOfChar[i];+//loop+over+every+char+and+add+it+to+the+string
++}
}
else+{
//+position+should+be+-1
//handle+if+no+dot+exists
}|code-block|syntax|javascript|3987739|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

<p>One approach you can make is splitting upp the string into chars in an array. Looping over the array from position 250 to position 0 and breaking when you find a dot. Take that index of the dot and splice the original array from the starting char, 0, to the dot which is the index value of that dot plus one as splice doesnt include the last value. Then turning that array into a string again.</p>

<pre><code>let string = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed in neque. Vivamus tellus. Donec magna. Donec consequat hendrerit magna. In iaculis neque eget nisi. Maecenas vehicula, leo eu commodo aliquam, sem dolor iaculis eros, vel mollis sem urna ac sapien. Integer mattis dui ut erat. Phasellus nibh magna, tempor vitae, dictum sed, vehicula sed, mauris. In enim arcu, porta vel, dictum eu, pretium a, ipsum. Donec cursus, lorem ac posuere viverra, sem tellus accumsan dolor, vel accumsan tortor est et est.";

let arrarOfChar = string.split(""); //turns string into array
let position = -1; //-1 indicates that no dot has been found
for(let i = 250 ; i &gt;= 0 ; i--) { //loop from 250 to 0
    if(arrarOfChar[i] == ".") { //if that char is equal to "."
    position = i; //set the position value to that
    break; //break the for loop
  }
}
if(position &gt; 0) { //only if we found a dot
  let newShortArrayOfChar = arrarOfChar.slice(0,position+1); //shorten the array from 0 to the dot index
  let finalString = ""; //this is the final string
  for(let i = 0; i &lt; newShortArrayOfChar.length ; i++) {
    finalString += newShortArrayOfChar[i]; //loop over every char and add it to the string
  }
}
else {
// position should be -1
//handle if no dot exists
}
</code></pre>


blocks|key|3987802|text|下面是一个非常简单的示例，它将字符串修剪为250个字符，然后向后查找第一个字符。如果没有找到，则返回全部250个字符，如果找到，则将其裁剪为该值。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3987803|​|3987804|var+maxLength+=+250;

function+test()+{
++var+input+=+document.getElementById('test').value;
++var+trimmed+=+input.substr(0,+maxLength);

++var+i+=+trimmed.length;
++while+(i+>+0)+{
++++if+(trimmed[i]+==+'.')+{
++++++break;
++++}
++++i--;
++}

++var+endResult+=+i+>+1+?+trimmed.substr(0,+i+%2B+1)+:+trimmed;
++endResult+%2B=+endResult.length+<+input.length+?+'+...'+:+'';
++document.getElementById('output').innerHTML+=+endResult;
}|code-block|syntax|javascript|3987805|.boxsizingBorder+{
++width:+100%25;
++-webkit-box-sizing:+border-box;
++-moz-box-sizing:+border-box;
++box-sizing:+border-box;
}|3987806|<button+onclick="test()">
++test
</button>
<textarea+id="test"+class="boxsizingBorder"+rows="5">Lorem+ipsum+dolor+sit+amet,+consectetur+adipiscing+elit.+Sed+in+neque.+Vivamus+tellus.+Donec+magna.+Donec+consequat+hendrerit+magna.+In+iaculis+neque+eget+nisi.+Maecenas+vehicula,+leo+eu+commodo+aliquam,+sem+dolor+iaculis+eros,+vel+mollis+sem+urna+ac+sapien.+Integer+mattis+dui+ut+erat.+Phasellus+nibh+magna,+tempor+vitae,+dictum+sed,+vehicula+sed,+mauris.+In+enim+arcu,+porta+vel,+dictum+eu,+pretium+a,+ipsum.+Donec+cursus,+lorem+ac+posuere+viverra,+sem+tellus+accumsan+dolor,+vel+accumsan+tortor+est+et+est.</textarea>
<p+id="output"></p>|3987807|3987808|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Q|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|R|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|K|3|L|5|F|7|T|8|@]|9|@]|A|$G|H]]|$1|M|3|C|5|6|7|U|8|@]|9|@]|A|$]]|$1|N|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|O|$]]

<p>Here is a pretty straightforward example that trims the string to 250 characters then walks backward looking for the first . if it doesn't find one then the entire 250 characters are returned and if it does it trims it to that .</p>

<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>var maxLength = 250;

function test() {
  var input = document.getElementById('test').value;
  var trimmed = input.substr(0, maxLength);

  var i = trimmed.length;
  while (i &gt; 0) {
    if (trimmed[i] == '.') {
      break;
    }
    i--;
  }

  var endResult = i &gt; 1 ? trimmed.substr(0, i + 1) : trimmed;
  endResult += endResult.length &lt; input.length ? ' ...' : '';
  document.getElementById('output').innerHTML = endResult;
}</code></pre>
<pre class="snippet-code-css lang-css prettyprint-override"><code>.boxsizingBorder {
  width: 100%;
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
}</code></pre>
<pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;button onclick="test()"&gt;
  test
&lt;/button&gt;
&lt;textarea id="test" class="boxsizingBorder" rows="5"&gt;Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed in neque. Vivamus tellus. Donec magna. Donec consequat hendrerit magna. In iaculis neque eget nisi. Maecenas vehicula, leo eu commodo aliquam, sem dolor iaculis eros, vel mollis sem urna ac sapien. Integer mattis dui ut erat. Phasellus nibh magna, tempor vitae, dictum sed, vehicula sed, mauris. In enim arcu, porta vel, dictum eu, pretium a, ipsum. Donec cursus, lorem ac posuere viverra, sem tellus accumsan dolor, vel accumsan tortor est et est.&lt;/textarea&gt;
&lt;p id="output"&gt;&lt;/p&gt;</code></pre>
</div>
</div>
</p>


<p>I am trying to shorted long string by number of characters (approximately) and finding sentence end (dot). Obviously this is not going to be 100% correct in all cases but its good enough. So for example, shorted string to 250 characters and find nearest dot as sentence end. </p>

<p>So having this:</p>

<pre><code>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed in neque. Vivamus tellus. Donec magna. Donec consequat hendrerit magna. In iaculis neque eget nisi. Maecenas vehicula, leo eu commodo aliquam, sem dolor iaculis eros, vel mollis sem urna ac sapien. Integer mattis dui ut erat. Phasellus nibh magna, tempor vitae, dictum sed, vehicula sed, mauris. In enim arcu, porta vel, dictum eu, pretium a, ipsum. Donec cursus, lorem ac posuere viverra, sem tellus accumsan dolor, vel accumsan tortor est et est.
</code></pre>

<p>Would create this:</p>

<pre><code>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed in neque. Vivamus tellus. Donec magna. Donec consequat hendrerit magna. In iaculis neque eget nisi. Maecenas vehicula, leo eu commodo aliquam, sem dolor iaculis eros, vel mollis sem urna ac sapien.
</code></pre>

<p>Things to consider I think:</p>

<p>If there is no dot in the string, shorten string by word boundary (so not to break a word) and add ellipsis (...) on the end which would be this function:</p>

<pre><code>function truncateString( str, n, useWordBoundary ){
    if (str.length &lt;= n) { return str; }
    var subString = str.substr(0, n-1);
    return (useWordBoundary 
       ? subString.substr(0, subString.lastIndexOf(' ')) 
       : subString) + "...";
};
</code></pre>

<p>How could one incorporate dot finding into this function?</p>


Javascript shorten string and find sentence end

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在尝试通过字符数(大约)来缩短长字符串，并找到句子结尾(点)。显然，这并不是在所有情况下都是100%正确的，但已经足够好了。例如，将字符串缩短为250个字符，然后查找最近的点作为句子结尾。所以，有了这个：Lorem ipsum dolor sit amet, consectetur adipiscing elit....

问Javascript缩短字符串并查找句子结尾
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