我如何分割一个字符串，以最大长度n断开？

Question

I have this string

It's important to remember that this function does NOT replace newlines 
with <br> tags. Rather, it inserts a <br> tag before each newline, but 
it still preserves the newlines themselves! This caused problems for me 
regarding a function I was writing -- I forgot the newlines were still 
being preserved. 

Using JavaScript, what is the fastest way to parse this into

var string1 = "It's important to remember that this function does ...";

This means, I want limit string that has n length and in the end it has '...'.

Help me.

Answer 1

Try this:

var shortenedString = originalString.substring(0, n) + "..."

It's a bit simple and will cut off words in the middle, but it does the trick.

Answer 2

Use substring method from string java class. And research better. I`m sure this question has been answered a lot of times. What do you want is

var string1 = string0.substring(0,n);

Answer 3

since you are using only javascript, here is polyfill taken from https://gist.github.com/timruffles/3377784

 var sample =`It's important to remember that this function does NOT replace newlines with <br> tags. Rather, it inserts a <br> tag before each newline, but it still preserves the newlines themselves! This caused problems for me regarding a function I was writing -- I forgot the newlines were still being preserved.`; var chunk = function(array,chunkSize) { return array.reduce(function(reducer,item,index) { reducer.current.push(item); if(reducer.current.length === chunkSize || index + 1 === array.length) { reducer.chunks.push(reducer.current); reducer.current = []; } return reducer; },{current:[],chunks: []}).chunks }; var data = chunk(sample.split(/[ ]+/), 10); data.forEach(function(line){ console.log(line.join(" ")) }); 

Answer 4

If you don't want to cut words in the middle:

  function shortener(s, n){ var ret = ""; if(s.charAt(n) !== " "){ var fullWords = s.substring(0, n).split(" ").length - 1; ret = s.split(" ").splice(0, fullWords).join(" "); } else{ ret = s.substring(0, n); } return ret + " ..."; } var s = "It's important to remember that this function does NOT replace newlines with <br> tags. Rather, it inserts a <br> tag before each newline, but it still preserves the newlines themselves! This caused problems for me regarding a function I was writing -- I forgot the newlines were still being preserved. "; console.log(shortener(s, 16)); console.log(shortener(s, 4)); console.log(shortener(s, 80)); 

Output:

• It's important ...
• It's ...
• It's important to remember that this function does NOT replace newlines with ...

Answer 5

Standard JavaScript offers three String methods that allow you to cut your string at position n :

• String.slice( begin [, end ] )
• String.substring( from [, to ] )
• String.substr( start [, length ] )

Just use one of these methods and add ... at the end of your result.

---

Demo 1

 var myString = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'; var n = 5; var output = ''; output += myString.slice(0, n) + '...' + '\\n<br>'; // Option 1 output += myString.substring(0, n) + '...' + '\\n<br>'; // Option 2 output += myString.substr(0, n) + '...'; // Option 3 document.body.innerHTML = output; 

See also this Fiddle .

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Demo 2

If you want to do this often, you may want to wrap this in a function :

 var myString = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'; var output = ''; function shorten(str, n) { if(n > 0) { return str.slice(0, n) + '...'; } return '...'; } output += shorten(myString, 20) + '\\n<br>'; output += shorten(myString, 8) + '\\n<br>'; output += shorten(myString, 0); document.body.innerHTML = output; 

See also this Fiddle .