Here is an example. Check the console for the result. The first two divs (not appended; above the <script> in the console) have the proper spacing and indention. However, the second two divs do not show the same formatting or white space as the original even though they are completely the same, but appended.
For example the input
var newElem = document.createElement('div');
document.body.appendChild(newElem);
var another = document.createElement('div');
newElem.appendChild(another);
console.log(document.body.innerHTML);
Gives the output
<div><div></div></div>
When I want it to look like
<div>
<div></div>
</div>
Is there any way to generate the proper white space between appended elements and retain that spacing when obtaining it using innerHTML (or a possible similar means)? I need to be able to visually display the hierarchy and structure of the page I'm working on.
I have tried appending it within an element that is in the actual HTML but it has the same behavior
I'd be okay with doing it using text nodes and line breaks as lincolnk suggested, but it needs to affect dynamic results, meaning I cannot use the same .createTextNode(' </br>') because different elements are in different levels of the hierarchy
No jQuery please
I think you're asking to be able to append elements to the DOM, such that the string returned from document.body.innerHTML will be formatted with indentation etc. as if you'd typed it into a text editor, right?
If so, something like this might work:
function indentedAppend(parent,child) {
var indent = "",
elem = parent;
while (elem && elem !== document.body) {
indent += " ";
elem = elem.parentNode;
}
if (parent.hasChildNodes() && parent.lastChild.nodeType === 3 && /^\s*[\r\n]\s*$/.test(parent.lastChild.textContent)) {
parent.insertBefore(document.createTextNode("\n" + indent), parent.lastChild);
parent.insertBefore(child, parent.lastChild);
} else {
parent.appendChild(document.createTextNode("\n" + indent));
parent.appendChild(child);
parent.appendChild(document.createTextNode("\n" + indent.slice(0,-2)));
}
}
demo: http://jsbin.com/ilAsAki/28/edit
I've not put too much thought into it, so you might need to play with it, but it's a starting point at least.
Also, i've assumed an indentation of 2 spaces as that's what you seemed to be using.
Oh, and you'll obviously need to be careful when using this with a <pre> tag or anywhere the CSS is set to maintain the whitespace of the HTML.
You can use document.createTextNode() to add a string directly.
var ft = document.createElement('div');
document.body.appendChild(ft);
document.body.appendChild(document.createTextNode(' '));
var another = document.createElement('div');
document.body.appendChild(another);
console.log(document.body.innerHTML);
Related
I created a word counting function and found a discrepancy. It produced different results counting the text words in html depending on if the element the html is enclosed in is part of the document.body or not. For example:
html = "<div>Line1</div><div>Line2<br></div>";
document.body.insertAdjacentHTML("afterend", '<div id="node1"></div>');
node1 = document.getElementById("node1");
node1.style.whiteSpace = 'pre-wrap';
node1.innerHTML = html;
node2 = document.createElement('div');
node2.style.whiteSpace = 'pre-wrap';
node2.innerHTML = html;
The white-space: pre-wrap style is applied so that the code in the html variable is rendered, in terms of line-breaks, consistently across browsers. In the above:
node1.innerText // is "Line1\nLine2\n" which counts as two words.
node2.innerText // is "Line1Line2" which counts as only one word.
My word count function is:
function countWords(s) {
s = (s+' ').replace(/^\s+/g, ''); // remove leading whitespace only
s = s.replace(/\s/g, ' '); // change all whitespace to spaces
s = s.replace(/[ ]{2,}/gi,' ')+' '; // change 2 or more spaces to 1
return s.split(' ').filter(String).length;
}
If I then did something like this in the Web Console:
node1.after(node2);
node2.innerText // is changed to "Line1\nLine2\n" which counts as two words.
My questions are:
Why is the white-space: pre-wrap style not being applied to node 2.innerText before it is inserted into the document.body?
If node 2 has to be a part of document.body in order to get a white-space: pre-wrap style node 2.innerText value, how do I do that without having to make node 2 visible?
I'm curious. When I crate a node element with createElement, where does that node element reside? It doesn't appear to be viewable in a Web Console Inspector inside or outside of the <html> tag and I can't find it in the document object.
This tipped me off that the discrepancy was something to do with if the node element being in the document.body or not: javascript createElement(), style problem.
Indeed, when the element is attached to the DOM, Element.innerText takes the rendered value into account - you can say, the visible output. For non-attached elements, there is no rendering. The CSS properties exist but are not executed.
If you want consistent results between attached and non-attached elements, use Element.textContent.
For more information, see https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/innerText
In follow-up to my question above, I needed to count the words in html text strings like this: <div>Line1</div><div>Line2<br></div> where the word count matched what it would be if that html was rendered in the displayed DOM
To summarize what others have said, when you create an element using createElement it isn’t inserted into the DOM yet and can’t be found when inspecting the DOM. Before the element is inserted into the DOM, the CSS properties exist but are not executed, so there is no rendering. When the element is inserted into the DOM, the CSS properties are executed, and the element is rendered according to the CSS.
Here's the html-string-to-rendered-html-text function I ended up using. This function strips the html tags but retains the "white space" so that the words can then be counted (with consistency across browsers, including IE 11).
var html = "<div>Line1</div><div>Line2<br></div>";
// Display the html string
var htmlts = document.getElementById("htmlts");
htmlts.innerText = html;
// Display a DOM render of the html string
var node1 = document.getElementById("node1");
node1.style.whiteSpace = 'pre-wrap';
node1.innerHTML = html;
// Display the innerText of the above DOM render
var node1ts = document.getElementById("node1ts");
node1ts.innerText = node1.innerText;
// Display the results of the htmlToText function
var node2ts = document.getElementById("node2ts");
node2ts.innerText = htmlToText(html);
// Adapted from https://stackoverflow.com/a/39157530
function htmlToText(html) {
var temp = document.createElement('div');
temp.style.whiteSpace = 'pre-wrap';
temp.style.position = "fixed"; // Overlays the normal flow
temp.style.left = "0"; // Placed flush left
temp.style.top = "0"; // Placed at the top
temp.style.zIndex = "-999"; // Placed under other elements
// opacity = "0" works for the entire temp element, even in IE 11.
temp.style.opacity = "0"; // Everything transparent
temp.innerHTML = html; // Render the html string
document.body.parentNode.appendChild(temp); // Places just before </html>
var out = temp.innerText;
// temp.remove(); // Throws an error in IE 11
// Solution from https://stackoverflow.com/a/27710003
temp.parentNode.removeChild(temp); // Removes the temp element
return out;
}
<html lang="en-US">
<body>
HTML String: <code id="htmlts"></code><br><br>
Visible Render of HTML String (for comparison): <div id="node1"></div><br>
Visible Render Text String: <code id="node1ts"></code><br>
Function Returned Text String: <Code id="node2ts"></code><br>
</body>
</html>
If you prefer to have the temporary element insert inside the body element, change document.body.parentNode.appendChild to document.body.appendChild.
As Noam had suggested, you can also use temp.style.top = "-1000px";.
To answer my curiosity question: before the element is "inserted into the DOM" it appears to be in a Shadow DOM or Shadow Dom-like space.
I have the following jQuery that mostly works:
$("article > p, article > div, article > ol > li, article > ul > li").contents().each(function() {
if (this.nodeType === 3) {
strippedValue = $.trim($(this).text());
doStuff(strippedValue);
}
if (this.nodeType === 1) {
strippedValue = $.trim($(this).html());
doStuff(strippedValue);
}
})
The problems comes when (inside doStuff()) I try to replace HTML tags. Here is a view of my elements:
And I'm trying to replace those <kbd> tags thusly:
newStr = newStr.replace(/<kbd>/g, " <b>");
newStr = newStr.replace(/<\/kbd>/g, "<b> ");
That doesn't work, and I'm seeing in the debugger that the <kbd> tags are seen as first-class children and looped separately. Whereas I want everything inside my selectors to be seen as a raw string so I can replace things. And I realize I'm asking for a contradiction, because .contents() means get children and their contents. So if I have a selector that is a direct parent of <kbd>, then <kdb> ceases to become a raw string and becomes instead a node that is being looped.
So it seems like my selectors are wrong BUT whenever I try to bring my selectors higher in the hierarchy, immediately I lose textual contents and I end up with a bunch of html with no contents inside the elements. (The screenshot shows good contents, as expected.)
So for example I tried this:
$("article").contents().each(function() {
...
}
...hoping that the selector looping would occur a little higher, and thus allow HTML tags further down to come through as raw text. But clearly I'm lost.
My objective is to simply perform a bunch of string replacements on the contents of the html. But there are two challenges with this:
The page contents load dynamically, with ajaxy calls or similar, so full contents are not available until about a second or two after page load.
When I try to grab high-level elements such as body, it ends up devoid of much of the textual contents. The selectors I currently have don't suffer from that problem; those get everything I want BUT then HTML/XML elements get looped instead of coming through as plain text so that I can perform replacements.
Why do you need to perform the modification on raw HTML? You could just replace the DOM elements directly (not to mention that this is much more reliable then using string replacement):
$('kbd').replaceWith(function() {
return ` <b>${this.textContent}</b> `;
// or directly create DOM elements:
// const b = document.createElement('b');
// b.textContent = this.textContent;
// return b;
});
console.log($('b').length);
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<kbd>hello world</kbd>
Of course you can still do string replacements where it makes sense, but you should work with DOM elements as much as possible.
I searched through a bunch of related questions that help with replacing site innerHTML using JavaScript, but most reply on targetting the ID or Class of the text. However, my can be either inside a span or td tag, possibly elsewhere. I finally was able to gather a few resources to make the following code work:
$("body").children().each(function() {
$(this).html($(this).html().replace(/\$/g,"%"));
});
The problem with the above code is that I randomly see some code artifacts or other issues on the loaded page. I think it has something to do with there being multiple "$" part of the website code and the above script is converting it to %, hence breaking things.using JavaScript or Jquery
Is there any way to modify the code (JavaScript/jQuery) so that it does not affect code elements and only replaces the visible text (i.e. >Here<)?
Thanks!
---Edit---
It looks like the reason I'm getting a conflict with some other code is that of this error "Uncaught TypeError: Cannot read property 'innerText' of undefined". So I'm guessing there are some elements that don't have innerText (even though they don't meet the regex criteria) and it breaks other inline script code.
Is there anything I can add or modify the code with to not try the .replace if it doesn't meet the regex expression or to not replace if it's undefined?
Wholesale regex modifications to the DOM are a little dangerous; it's best to limit your work to only the DOM nodes you're certain you need to check. In this case, you want text nodes only (the visible parts of the document.)
This answer gives a convenient way to select all text nodes contained within a given element. Then you can iterate through that list and replace nodes based on your regex, without having to worry about accidentally modifying the surrounding HTML tags or attributes:
var getTextNodesIn = function(el) {
return $(el)
.find(":not(iframe, script)") // skip <script> and <iframe> tags
.andSelf()
.contents()
.filter(function() {
return this.nodeType == 3; // text nodes only
}
);
};
getTextNodesIn($('#foo')).each(function() {
var txt = $(this).text().trim(); // trimming surrounding whitespace
txt = txt.replace(/^\$\d$/g,"%"); // your regex
$(this).replaceWith(txt);
})
console.log($('#foo').html()); // tags and attributes were not changed
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="foo"> Some sample data, including bits that a naive regex would trip up on:
foo<span data-attr="$1">bar<i>$1</i>$12</span><div>baz</div>
<p>$2</p>
$3
<div>bat</div>$0
<!-- $1 -->
<script>
// embedded script tag:
console.log("<b>$1</b>"); // won't be replaced
</script>
</div>
I did it solved it slightly differently and test each value against regex before attempting to replace it:
var regEx = new RegExp(/^\$\d$/);
var allElements = document.querySelectorAll("*");
for (var i = 0; i < allElements.length; i++){
var allElementsText = allElements[i].innerText;
var regExTest = regEx.test(allElementsText);
if (regExTest=== true) {
console.log(el[i]);
var newText = allElementsText.replace(regEx, '%');
allElements[i].innerText=newText;
}
}
Does anyone see any potential issues with this?
One issue I found is that it does not work if part of the page refreshes after the page has loaded. Is there any way to have it re-run the script when new content is generated on page?
Hi I am trying to add a html with a SPACE after in a contenteditable div;
The problem is that, with above code it only return the content of the first DIV and ignore everything else.
var tdiv = document.createElement('div');
tdiv.innerHTML = '<div>testing html</div> ';
var replacment = tdiv.firstChild; //
el.insertNode(replacment); // it is just the purpose, "el" is the HTML element
With this the nbsp will be removed.
If you want all children of tdiv to be added to el then try
var el = document.getElementById('x')
while (tdiv.firstChild) {
el.appendChild(tdiv.firstChild);
}
Demo: Fiddle
You can create an element with an nbsp in it like this:
var div = document.createElement("div");
div.innerHTML = " ";
If you really just want an element with a space of text, you can just create a text node:
var div = document.createElement("div");
div.appendChild(document.createTextNode(" "));
Looking at your question again, it is actually quite unclear what you're really asking and it appears that there are many different things your question might mean. So, this is just one possibility for what you might be asking.
If you want to add it as an element, then you need to put it in some sort of container since a non-breakingspace isn't an element by itself. You can wrap it in a <span> element like this and then insert the <span>.
var span = document.createElement("span");
span.innerHTML = " ";
el.appendChild(span);
Or, maybe it works just fine to insert a text node with a space in it:
el.appendChild(document.createTextNode(" "));
After Arun P Johny Idea I resolved like this:
var replacement = '<div>testing</div> ',startAfter,i,tdiv = document.createElement('div');
tdiv.innerHTML = replacment;
replacment=document.createDocumentFragment();
while(i=tdiv.firstChild) replacment.appendChild(i);
startAfter = replacment.lastChild;
// This is my extra code to the contenteditable div insert and positioning the caret - this.range is my selection range.
this.range.insertNode(replacment);
this.range.setStartAfter(startAfter);
Thank you all, even for the down votes :P
I have a string which contains a lot of text, text, in my JavaScript file. I also have an element, div#container that is styled (using separate CSS) with potentially nonstandard line-height, font-size, font-face, and maybe others. It has a fixed height and width.
I'd like to get the maximum amount of text that can fit into div#container without any overflow from the string. What's the best way of doing this?
This needs to be able to work with text formatted with tags, for example:
<strong>Hello person that is this is long and may take more than a</strong>
line and so on.
Currently, I've got a JQuery plugin that works for plain text, code follows:
// returns the part of the string that cannot fit into the object
$.fn.func = function(str) {
var height = this.height();
this.height("auto");
while(true) {
if(str == "") {
this.height(height);
return str; // the string is empty, we're done
}
var r = sfw(str); // r = [word, rest of String] (sfw is a split first word function defined elsewhere
var w = r[0], s = r[1];
var old_html = this.html();
this.html(old_html + " " + w);
if(this.height() > height)
{
this.html(old_html);
this.height(height);
return str; // overflow, return to last working version
}
str = s;
}
}
UPDATE:
The data looks like this:
<ol>
<li>
<h2>Title</h2>
<ol>
<li>Character</li>
<ol>
<li>Line one that might go on a long time, SHOULD NOT BE BROKEN</li>
<li>Line two can be separated from line one, but not from itself</li>
</ol>
</ol>
<ol>
<li>This can be split from other</li>
<ol>
<li>Line one that might go on a long time, SHOULD NOT BE BROKEN</li>
<li>Line two can be separated from line one, but not from itself</li>
</ol>
</ol>
</li> <li>
<h2>Title</h2>
<ol>
<li>Character</li>
<ol>
<li>Line one that might go on a long time, SHOULD NOT BE BROKEN</li>
<li>Line two can be separated from line one, but not from itself</li>
</ol>
</ol>
<ol>
<li>This can be split from other</li>
<ol>
<li>Line one that might go on a long time, SHOULD NOT BE BROKEN</li>
<li>Line two can be separated from line one, but not from itself</li>
</ol>
</ol>
</li>
</ol>
well, let me try to solve it ;) actually thinking about solution I noticed that I don't know enough about requirements you have, so I decided to develop simple JavaScript code and show you result; after trying it you can tell me what's wrong so I can fix/change it, deal?
I used pure JavaScript, no jQuery (it can be rewritten if needed). The principle is similar to your jQuery plugin:
we take characters one by one (instead of words as sfw function does; it can be changed)
if it is part of opening tag, browser does not show it, so I didn't processed it special way, just appended one by one characters from tag name and checked height of container... no idea if it is that bad. I mean when I write container.innerHTML = "My String has a link <a href='#'"; in browser I see "My String has a link", so "unfinished" tag does not influence size of container (at least in all browsers where I tested)
check size of container, and if it is bigger than we expect it to be, then previous string (actually current string without last character) is what we are looking for
now we have to close all opening tags, which are not closed because of cutting
HTML page to test it:
<html>
<head>
<style>
div {
font-family: Arial;
font-size: 20px;
width: 200px;
height: 25px;
overflow: hidden;
}
</style>
</head>
<body>
<div id="container"> <strong><i>Strong text with link </i> and </strong> simple text </div>
<script>
/**
* this function crops text inside div element, leaving DOMstructure valid (as much as possible ;).
* also it makes visible part as "big" as possible, meaning that last visible word will be split
* to show its first letters if possible
*
* #param container {HTMLDivElement} - container which can also have html elements inside
* #return {String} - visible part of html inside div element given
*/
function cropInnerText( container ) {
var fullText = container.innerHTML; // initial html text inside container
var realHeight = container.clientHeight; // remember initial height of the container
container.style.height = "auto"; // change height to "auto", now div "fits" its content
var i = 0;
var croppedText = "";
while(true) {
// if initial container content is the same that cropped one then there is nothing left to do
if(croppedText == fullText) {
container.style.height = realHeight + "px";
return croppedText;
}
// actually append fullText characters one by one...
var nextChar = fullText.charAt( i );
container.innerHTML = croppedText + nextChar;
// ... and check current height, if we still fit size needed
// if we don't, then we found that visible part of string
if ( container.clientHeight > realHeight ) {
// take all opening tags in cropped text
var openingTags = croppedText.match( /<[^<>\/]+>/g );
if ( openingTags != null ) {
// take all closing tags in cropped text
var closingTags = croppedText.match( /<\/[^<>]+>/g ) || [];
// for each opening tags, which are not closed, in right order...
for ( var j = openingTags.length - closingTags.length - 1; j > -1; j-- ) {
var openingTag;
if ( openingTags[j].indexOf(' ') > -1 ) {
// if there are attributes, then we take only tag name
openingTag = openingTags[j].substr(1, openingTags[j].indexOf(' ')-1 ) + '>';
}
else {
openingTag = openingTags[j].substr(1);
}
// ... close opening tag to have valid html
croppedText += '</' + openingTag;
}
}
// return height of container back ...
container.style.height = realHeight + "px";
// ... as well as its visible content
container.innerHTML = croppedText;
return croppedText;
}
i++;
croppedText += nextChar;
}
}
var container = document.getElementById("container");
var str = cropInnerText( container );
console.info( str ); // in this case it prints '<strong><i>Strong text with link</i></strong>'
</script>
</body>
Possible improvements / changes:
I do not create any new DOM elements, so I just reuse current container (to be sure I take into account all css styles); this way I change its content all the time, but after taking visible text you can write fullText back into container if needed (which I also do not change)
Processing original text word by word will let us make less changes in DOM (we will write word by word instead of character by character), so this way should be faster. You already have sfw function, so you can change it easily.
If we have two words "our sentence", it is possible that visible will be only first one ("our"), and "sentence" should be cut (overflow:hidden will work this way). In my case, I will append character by character, so my result can be "our sent". Again, this is not a complex part of algorithm, so based on your jQuery plugin code, you can change mine to work with words.
Questions, remarks, bugs found are welcome ;) I tested it in IE9, FF3.6, Chrome 9
UPDATE: Accroding to an issue with <li>, <h1> ... E.g. I have container with content:
<div id="container"> <strong><i>Strong text with <ul><li>link</li></ul> </i> and </strong> simple text </div>
In this case browser behaves this way (string by string what is in container and what I see it shows according to the algorithm):
...
"<strong><i>Strong text with <" -> "<strong><i>Strong text with <"
"<strong><i>Strong text with <u" -> "<strong><i>Strong text with "
"<strong><i>Strong text with <ul" -> "<strong><i>Strong text with <ul></ul>" // well I mean it recognizes ul tag and changes size of container
and result of algorithm is string "<strong><i>Strong text with <u</i></strong>" - with "<u", what is not nice. What I need to process in this case is that if we found our result string ("<strong><i>Strong text with <u" according to the algorithm), we need to removed last "unclosed" tag ("<u" in our case), so before closing tags to have valid html I added the following:
...
if ( container.clientHeight > realHeight ) {
/* start of changes */
var unclosedTags = croppedText.match(/<[\w]*/g);
var lastUnclosedTag = unclosedTags[ unclosedTags.length - 1 ];
if ( croppedText.lastIndexOf( lastUnclosedTag ) + lastUnclosedTag.length == croppedText.length ) {
croppedText = croppedText.substr(0, croppedText.length - lastUnclosedTag.length );
}
/* end of changes */
// take all opening tags in cropped text
...
probably a bit lazy implementation, but it can be tuned if it slows down. What is done here
take all tags without > (in our case it returns ["<strong", "<i", "<u"]);
take last one ("<u")
if it is end of croppedText string, then we remove it
after doing it, the result string becomes "<strong><i>Strong text with </i></strong>"
UPDATE2 thank you for example, so I see that you don't have just nested tags, but they also have "tree" structure, indeed I didn't take it into account, but it still can be fixed ;) At the beginning I wanted to write my appropriate "parser", but all the time I get an example when I does not work, so I thought it is better to find already written parser, and there is one: Pure JavaScript HTML Parser. There is also one shag to it:
While this library doesn't cover the
full gamut of possible weirdness that
HTML provides, it does handle a lot of
the most obvious stuff.
but for your example it works; that library didn't take into account position of opening tag, but
we rely that original html structure is fine (not broken);
we close tags at the end of the result "string" (so this is ok)
I think that with that assumptions this library is nice to use. Then result function looks like:
<script src="http://ejohn.org/files/htmlparser.js"></script>
<script>
function cropInnerText( container ) {
var fullText = container.innerHTML;
var realHeight = container.clientHeight;
container.style.height = "auto";
var i = 0;
var croppedText = "";
while(true) {
if(croppedText == fullText) {
container.style.height = realHeight + "px";
return croppedText;
}
var nextChar = fullText.charAt( i );
container.innerHTML = croppedText + nextChar;
if ( container.clientHeight > realHeight ) {
// we still have to remove unended tag (like "<u" - with no closed bracket)
var unclosedTags = croppedText.match(/<[\w]*/g);
var lastUnclosedTag = unclosedTags[ unclosedTags.length - 1 ];
if ( croppedText.lastIndexOf( lastUnclosedTag ) + lastUnclosedTag.length == croppedText.length ) {
croppedText = croppedText.substr(0, croppedText.length - lastUnclosedTag.length );
}
// this part is now quite simple ;)
croppedText = HTMLtoXML(croppedText);
container.style.height = realHeight + "px";
container.innerHTML = croppedText ;
return croppedText;
}
i++;
croppedText += nextChar;
}
}
</script>
To get longest possible first line:
Create a DIV with visibility:hidden; (so it will have dimension) but position it as position:absolute; so it won't break your page flow
set its type style to the same values as your resulting DIV
Set it's height the same as resulting DIV but keep width:auto;
Add text to it
Keep cutting off text until width drops below resulting DIV's width.
The result is the text you can put in.
Adjust the algorithm if you need to find amount of lines that fit into container to keep height:auto; and set fixed width.
The same technique is used by auto-adjusting textareas that auto-grow while users type in text.
To solve this, you're going to need additional information:
where should I 'chop' the input text
having chopped it, how do I repair the two halves so that I can stuff each one into a DIV?
As for the 'where to chop' question, you'll probably have to inject unique <a name="uniq"/> anchor tags at strategic points in your input string (say ... before each opening tag in the input?). Then, you can test the layed-out position of each anchor and find where to break the input.
Having found the most logical point to break, you'll need to add tags at the end of the first half to close it off, and add tags at the front of the next half to open it. So when you parsed your input string to find the opening tags previously, you kept a list of the 'tag stack' when you injected the <a/>. Lookup the tag stack that's relevant for this paritcular and then add the tags as required.
I can spot 2 gotchas with this:
you'll need to keep more information about each break if the input tags have attributes
you may need to treat some tags as 'unbreakable' and break at an earlier <a/> instead
Ultimately, it seems to me you're waiting for HTML5's column construct.
Are you just trying to format the first line in a paragraph? Would the CSS :first-line pseudo-selector work for your application?
You could use getComputedStyle to find out the width of an inline element (i.e. it has the display: inline property):
window.getComputedStyle(element, null).getPropertyValue("width");
If it turns out that this element's width is larger than its container's width, you would remove some text step by step until it fits in.