CODEWITHSUNDEEP
javascripthtml
Leminnes
Leminnes

Reputation: 133

Split string at space after certain number of characters in Javascript

I am attempting to create a tool that takes an input text and splits it into chunks of text at a certain # of characters. However, I need to make sure it does not split the text in the middle of a word.

In my case, I am splitting the string after 155 characters.

I've done quite a lot of searching to try and find a solution, but I fear it may be more complicated than my knowledge of Javascript allows me to figure out. I believe I just need to make some sort of logic that has the splitter backtrack to a space to split if it is in the middle of a word, but I am not sure how to write out such a thing.

Here is my javascript code at the moment:

function splitText() {
    "use strict";
    var str = document.getElementById("user_input").value;
    var size = 195;
    var chunks = new Array(Math.ceil(str.length / size)),
        nChunks = chunks.length;

    var newo = 0;
    for (var i = 0, o = 0; i < nChunks; ++i, o = newo) {
          newo += size;
          chunks[i] = str.substr(o, size);
    }

    var newq = 0;
    for (var x = 0, q = 0; x < nChunks; ++x, q = newq) {
        $("#display").append("<textarea readonly>" + chunks[x] + "</textarea><br/>");
    }
}

And here is my HTML:

<body>
    <content>
        <h1>Text Splitter</h1>
        <form>
            <label>Enter a Message</label>
            <input type="text" name="message" id="user_input">
        </form>
        <form>
            <input type="button" onclick="splitText();" id="submit" value="Submit!"> <br/>
        </form>
        <label>Your split message: </label>
        <p><span id='display'></span></p>
    </content>
</body>

Here is the code in its current working form, if you'd like to take a look: https://jsfiddle.net/add4s7rs/7/

Thank you! I appreciate any assistance!

Upvotes: 12

Views: 19625

Answers (5)

Nick
Nick

Reputation: 147266

A short and simple way to split a string into chunks up to a certain length using a regexp:

const chunks = str.match(/.{1,154}(?:\s|$)/g);

some examples:

const str = 'the quick brown fox jumps over the lazy dog';

console.log(str.match(/.{1,10}(?:\s|$)/g))
console.log(str.match(/.{1,15}(?:\s|$)/g))

This works because quantifiers (in this case {1,154}) are by default greedy and will attempt to match as many characters as they can. putting the (\s|$) behind the .{1,154} forces the match to terminate on a whitespace character or the end of the string. So .{1,154}(\s|$) will match up to 154 characters followed by a whitespace character. The /g modifier then makes it continue to match through the entire string.

To put this in the context of your function:

function splitText() {
    "use strict";
    var str = document.getElementById("user_input").value;
    var chunks = str.match(/.{1,154}(?:\s|$)/g);

    chunks.forEach(function (i,x) {
        $("#display").append("<textarea readonly>" + chunks[x] + "</textarea><br/>");
    });
}

Note (as has been pointed out in the comments) that this code will fail if one of the words in the string is longer than the length of the chunks.

Note also that this code will leave a trailing space on the end of the split strings; if you want to avoid that change the last group to a lookahead and insist that the first character not be whitespace:

const str = 'the quick brown fox jumps over the lazy dog';

console.log(str.match(/\S.{1,9}(?=\s|$)/g))
console.log(str.match(/\S.{1,14}(?=\s|$)/g))

Upvotes: 38

Shubham Ambastha
Shubham Ambastha

Reputation: 314

With Regex and Pure Javascript. This will take array of strings and return array containing chunks of strings based on the given length.

const chunkString = (str, length) => {
  return str.match(new RegExp(".{1," + length + "}", "g"));
};

const chunkStringArray = (arr) => {
  return arr.map((el) => chunkString(el, 200)).flat();
};

Upvotes: 0

Cory Kleiser
Cory Kleiser

Reputation: 2034

you could use a simple function like this:

function split(string) {
  for(i=154; i>=0; i--) {
    if(string.charAt(i) == " ") {
      var newString1 = string.slice(0, i);
      var newString2 = string.slice(i);
    }
  }
}

Instead of assigning to separate strings you can always put them into an array if you'd like as well.

Upvotes: 1

TheThirdRekt
TheThirdRekt

Reputation: 35

This solution goes on the logic of having a maximum chunk size and then reducing that size if need be to fit your word. Uses a while loop and a little bit of C style logic.

function splitText() {
    "use strict";

    var str = document.getElementById("user_input").value;

    // Maximum allowed chunk size
    let MAX_CHUNK_SIZE = 155;
    let chunks = new Array();
    let current_chunk_position = 0;

    while(current_chunk_position < str.length){

        let current_substring = str.substr(current_chunk_position, MAX_CHUNK_SIZE);

        let last_index = current_substring.lastIndexOf(" ") > 0 ? current_substring.lastIndexOf(" ") : MAX_CHUNK_SIZE;

        let chunk = str.substr(current_chunk_position, last_index);
        chunks.push(chunk);

        current_chunk_position += last_index;
    }

    var newq = 0;
    for (var x = 0, q = 0; x < nChunks; ++x, q = newq) {
        $("#display").append("<textarea readonly>" + chunks[x] + "</textarea><br/>");
    }
}

Upvotes: 0

Scott Marcus
Scott Marcus

Reputation: 65873

A more simple approach would be to split the entered text into an array of the individual words and then loop through the array and re-build the string, keeping a count of whether adding the next word in the array will put you over your max size.

Also, note that you should keep all of your form elements inside a single form.

Lastly, you should not use inline HTML event attributes (onclick, etc.). That was a technique we used 20+ years ago before we had standards and best-practices and, unfortunately the use of the technique is so prolific, it just will not die the abrupt death it deserves. There are many reasons not to code this way and instead use the modern approach of doing all event handling with .addEventListener() in a separate JavaScript.

// Don't set variables to properties of DOM elements, set them to the element
// itself so that if you ever want a different property value, you don't have to
// re-scan the DOM for the same element again.
var str = document.getElementById("user_input");
var output = document.getElementById("display");

document.getElementById("go").addEventListener("click",function(){
    "use strict";
    const size = 155; // Constant is more appropriate here
    var words = str.value.split(/\s+/g); // Create array of all words in field
    
    var finalString = "";
    
    // Loop through array
    for(var i = 0; i < words.length; i++){
      if((finalString + " " + words[i]).length <= size){
        finalString += " " + words[i];
      } else {
        break; // Max size exceeded - quit loop!
      }
    }
    
    // Update field with correct value
    output.textContent = finalString;
    console.log(finalString.length);
});
textarea {
  width:500px;
  height:100px;
}
<h1>Text Splitter</h1>
        <form>
            <label>Enter a Message
            <textarea name="message" id="user_input">This is a test of the emergency broadcast system. If this had been an actual emergency, you would have been informed as to what instructions you should follow in order to remain safe at all times.</textarea></label>
            <input type="button" id="go" value="Submit!"><br>
        </form>
        <label>Your split message: </label>
        <p><span id='display'></span></p>

Upvotes: 0

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