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Auto-adjusting textarea to be the same height as inner-text onkeydown

I'm trying to auto adjust the height of a textarea onkeydown, but it's only working partially. When you're typing text into the textarea, it auto-adjust the height of the textarea per new line of text, which is what I want. But when you're backspacing the text, it auto-adjust the height of the textarea per character-backspaced when you're on the last 5 characters of every last line. What am I doing wrong?
#textarea {
overflow: hidden;
}
<textarea id = 'textarea' onkeydown = "adjust()"></textarea>
<script>
function adjust() {
document.getElementById("textarea").style.height = document.getElementById("textarea").scrollHeight+'px';
} //end of function adjust()
</script>

Create your textarea:
<textarea id="textarea" onkeyup="InputAdjust(this)"></textarea>
then create a function to do the auto height
<script>
function InputAdjust(o) {
o.style.height = "1px";
o.style.height = (25+o.scrollHeight)+"px";
}
</script>
now its +25px, you can change it.
example: https://jsfiddle.net/urp4nbxf/1/

Try this :
$("#textarea").on("keydown",function(){
if($(this).css("height").replace("px","") < $('#textarea').get(0).scrollHeight - 5)
$(this).css("height",($('#textarea').get(0).scrollHeight-5) + "px");
});
Example : https://jsfiddle.net/DinoMyte/dpx1Ltn2/2/

The code below will work, but you will have to manually count how many characters fit in per row, in the textarea. How many characters fit in per row will depend on the cols of the textarea, and of course the font-size of the text.
#textarea {
overflow: hidden;
}
<textarea id = 'textarea' cols = '7' rows = '1' onkeydown = "adjust()"></textarea>
<script>
function adjust() {
var maxCharactersPerColumn = 9; //You have to manually count how many characters fits in per row
var key = event.keyCode;
if (key == 8 || key == 46) {
var length = document.getElementById("textarea").value.length-2;
} //end of if (key == 8 || key == 46)
else {
var length = document.getElementById("textarea").value.length;
} //end of else !(key == 8 || key == 46)
var rows = Math.floor(length/maxCharactersPerColumn)+1;
document.getElementById("textarea").rows = rows;
} //end of function adjust()
</script>

Traversing contenteditable paragraphs with arrow keys

I'm try to traverse between contenteditable paragraphs using the arrow keys. I can't put a containing div around all paragraphs as the may be divided by other non-editable elements.
I need to be able to determine the character length of the first line so that when the up arrow key is pressed when the cursor is on the line then it will jump up to the previous paragraph - hopefully keeping the cursor position relative to the line.
I can get the cursor index with:
function cursorIndex() {
return window.getSelection().getRangeAt(0).startOffset;
}
and set it with: as found here - Javascript Contenteditable - set Cursor / Caret to index
var setSelectionRange = function(element, start, end) {
var rng = document.createRange(),
sel = getSelection(),
n, o = 0,
tw = document.createTreeWalker(element, NodeFilter.SHOW_TEXT, null, null);
while (n = tw.nextNode()) {
o += n.nodeValue.length;
if (o > start) {
rng.setStart(n, n.nodeValue.length + start - o);
start = Infinity;
}
if (o >= end) {
rng.setEnd(n, n.nodeValue.length + end - o);
break;
}
}
sel.removeAllRanges();
sel.addRange(rng);
};
var setCaret = function(element, index) {
setSelectionRange(element, index, index);
};
Say the cursor is at the top row of the third paragraph and the up arrow is pressed, I would like it to jump to the bottom row of the second paragraph
http://jsfiddle.net/Pd52U/2/

Looks like there's no easy way to do this, I have the following working example. There's a bit of processing so it's a little slow and it can be out by the odd character when moving up and down between paragraph.
Please inform me of any improvements that can be made.
http://jsfiddle.net/zQUhV/47/
What I've done is split the paragraph by each work, insert them into a new element one by one, checking for a height change - when it does change a new line was added.
This function returns an array of line objects containing the line text, starting index and end index:
(function($) {
$.fn.lines = function(){
words = this.text().split(" "); //split text into each word
lines = [];
hiddenElement = this.clone(); //copies font settings and width
hiddenElement.empty();//clear text
hiddenElement.css("visibility", "hidden");
jQuery('body').append(hiddenElement); // height doesn't exist until inserted into document
hiddenElement.text('i'); //add character to get height
height = hiddenElement.height();
hiddenElement.empty();
startIndex = -1; // quick fix for now - offset by one to get the line indexes working
jQuery.each(words, function() {
lineText = hiddenElement.text(); // get text before new word appended
hiddenElement.text(lineText + " " + this);
if(hiddenElement.height() > height) { // if new line
lines.push({text: lineText, startIndex: startIndex, endIndex: (lineText.length + startIndex)}); // push lineText not hiddenElement.text() other wise each line will have 1 word too many
startIndex = startIndex + lineText.length +1;
hiddenElement.text(this); //first word of the next line
}
});
lines.push({text: hiddenElement.text(), startIndex: startIndex, endIndex: (hiddenElement.text().length + startIndex)}); // push last line
hiddenElement.remove();
lines[0].startIndex = 0; //quick fix for now - adjust first line index
return lines;
}
})(jQuery);
Now you could use that to measure the number of character up until the point of the cursor and apply that when traversing paragraph to keep the cursor position relative to the start of the line. However that can produce wildly inaccurate results when considering the width of an 'i' to the width of an 'm'.
Instead it would be better to find the width of the line up to the point of the cursor:
function distanceToCaret(textElement,caretIndex){
line = findLineViaCaret(textElement,caretIndex);
if(line.startIndex == 0) {
// +1 needed for substring to be correct but only first line?
relativeIndex = caretIndex - line.startIndex +1;
} else {
relativeIndex = caretIndex - line.startIndex;
}
textToCaret = line.text.substring(0, relativeIndex);
hiddenElement = textElement.clone(); //copies font settings and width
hiddenElement.empty();//clear text
hiddenElement.css("visibility", "hidden");
hiddenElement.css("width", "auto"); //so width can be measured
hiddenElement.css("display", "inline-block"); //so width can be measured
jQuery('body').append(hiddenElement); // doesn't exist until inserted into document
hiddenElement.text(textToCaret); //add to get width
width = hiddenElement.width();
hiddenElement.remove();
return width;
}
function findLineViaCaret(textElement,caretIndex){
jQuery.each(textElement.lines(), function() {
if(this.startIndex <= caretIndex && this.endIndex >= caretIndex) {
r = this;
return false; // exits loop
}
});
return r;
}
Then split the target line up into characters and find the point that closest matches the width above by adding characters one by one until the point is reached:
function getCaretViaWidth(textElement, lineNo, width) {
line = textElement.lines()[lineNo-1];
lineCharacters = line.text.replace(/^\s+|\s+$/g, '').split("");
hiddenElement = textElement.clone(); //copies font settings and width
hiddenElement.empty();//clear text
hiddenElement.css("visibility", "hidden");
hiddenElement.css("width", "auto"); //so width can be measured
hiddenElement.css("display", "inline-block"); //so width can be measured
jQuery('body').append(hiddenElement); // doesn't exist until inserted into document
if(width == 0) { //if width is 0 index is at start
caretIndex = line.startIndex;
} else {// else loop through each character until width is reached
hiddenElement.empty();
jQuery.each(lineCharacters, function() {
text = hiddenElement.text();
prevWidth = hiddenElement.width();
hiddenElement.text(text + this);
elWidth = hiddenElement.width();
caretIndex = hiddenElement.text().length + line.startIndex;
if(hiddenElement.width() > width) {
// check whether character after width or before width is closest
if(Math.abs(width - prevWidth) < Math.abs(width - elWidth)) {
caretIndex = caretIndex -1; // move index back one if previous is closes
}
return false;
}
});
}
hiddenElement.remove();
return caretIndex;
}
That with the following keydown function is enough to traverse pretty accurately between contenteditable paragraphs:
$(document).on('keydown', 'p[contenteditable="true"]', function(e) {
//if cursor on first line & up arrow key
if(e.which == 38 && (cursorIndex() < $(this).lines()[0].text.length)) {
e.preventDefault();
if ($(this).prev().is('p')) {
prev = $(this).prev('p');
getDistanceToCaret = distanceToCaret($(this), cursorIndex());
lineNumber = prev.lines().length;
caretPosition = getCaretViaWidth(prev, lineNumber, getDistanceToCaret);
prev.focus();
setCaret(prev.get(0), caretPosition);
}
// if cursor on last line & down arrow
} else if(e.which == 40 && cursorIndex() >= $(this).lastLine().startIndex && cursorIndex() <= ($(this).lastLine().startIndex + $(this).lastLine().text.length)) {
e.preventDefault();
if ($(this).next().is('p')) {
next = $(this).next('p');
getDistanceToCaret = distanceToCaret($(this), cursorIndex());
caretPosition = getCaretViaWidth(next, 1, getDistanceToCaret);
next.focus();
setCaret(next.get(0), caretPosition);
}
//if start of paragraph and left arrow
} else if(e.which == 37 && cursorIndex() == 0) {
e.preventDefault();
if ($(this).prev().is('p')) {
prev = $(this).prev('p');
prev.focus();
setCaret(prev.get(0), prev.text().length);
}
// if end of paragraph and right arrow
} else if(e.which == 39 && cursorIndex() == $(this).text().length) {
e.preventDefault();
if ($(this).next().is('p')) {
$(this).next('p').focus();
}
};

Find out the 'line' (row) number of the cursor in a textarea

I would like to find out and keep track of the 'line number' (rows) of the cursor in a textarea. (The 'bigger picture' is to parse the text on the line every time a new line is created/modified/selected, if of course the text was not pasted in. This saves parsing the whole text un-necessarily at set intervals.)
There are a couple of posts on StackOverflow however none of them specifically answer my question, most questions are for cursor position in pixels or displaying lines numbers besides the textarea.
My attempt is below, it works fine when starting at line 1 and not leaving the textarea. It fails when clicking out of the textarea and back onto it on a different line. It also fails when pasting text into it because the starting line is not 1.
My JavaScript knowledge is pretty limited.
<html>
<head>
<title>DEVBug</title>
<script type="text/javascript">
var total_lines = 1; // total lines
var current_line = 1; // current line
var old_line_count;
// main editor function
function code(e) {
// declare some needed vars
var keypress_code = e.keyCode; // key press
var editor = document.getElementById('editor'); // the editor textarea
var source_code = editor.value; // contents of the editor
// work out how many lines we have used in total
var lines = source_code.split("\n");
var total_lines = lines.length;
// do stuff on key presses
if (keypress_code == '13') { // Enter
current_line += 1;
} else if (keypress_code == '8') { // Backspace
if (old_line_count > total_lines) { current_line -= 1; }
} else if (keypress_code == '38') { // Up
if (total_lines > 1 && current_line > 1) { current_line -= 1; }
} else if (keypress_code == '40') { // Down
if (total_lines > 1 && current_line < total_lines) { current_line += 1; }
} else {
//document.getElementById('keycodes').innerHTML += keypress_code;
}
// for some reason chrome doesn't enter a newline char on enter
// you have to press enter and then an additional key for \n to appear
// making the total_lines counter lag.
if (total_lines < current_line) { total_lines += 1 };
// putput the data
document.getElementById('total_lines').innerHTML = "Total lines: " + total_lines;
document.getElementById('current_line').innerHTML = "Current line: " + current_line;
// save the old line count for comparison on next run
old_line_count = total_lines;
}
</script>
</head>
<body>
<textarea id="editor" rows="30" cols="100" value="" onkeydown="code(event)"></textarea>
<div id="total_lines"></div>
<div id="current_line"></div>
</body>
</html>

You would want to use selectionStart to do this.
<textarea onkeyup="getLineNumber(this, document.getElementById('lineNo'));" onmouseup="this.onkeyup();"></textarea>
<div id="lineNo"></div>
<script>
function getLineNumber(textarea, indicator) {
indicator.innerHTML = textarea.value.substr(0, textarea.selectionStart).split("\n").length;
}
</script>
This works when you change the cursor position using the mouse as well.

This is tough because of word wrap. It's a very easy thing to count the number of line breaks present, but what happens when the new row is because of word wrap? To solve this problem, it's useful to create a mirror (credit: github.com/jevin). Here's the idea:
Create a mirror of the textarea
Send the content from the beginning of the textarea to the cursor to the mirror
Use the height of the mirror to extract the current row
On JSFiddle
jQuery.fn.trackRows = function() {
return this.each(function() {
var ininitalHeight, currentRow, firstIteration = true;
var createMirror = function(textarea) {
jQuery(textarea).after('<div class="autogrow-textarea-mirror"></div>');
return jQuery(textarea).next('.autogrow-textarea-mirror')[0];
}
var sendContentToMirror = function (textarea) {
mirror.innerHTML = String(textarea.value.substring(0,textarea.selectionStart-1)).replace(/&/g, '&').replace(/"/g, '"').replace(/'/g, ''').replace(/</g, '<').replace(/>/g, '>').replace(/\n/g, '<br />') + '.<br/>.';
calculateRowNumber();
}
var growTextarea = function () {
sendContentToMirror(this);
}
var calculateRowNumber = function () {
if(firstIteration){
ininitalHeight = $(mirror).height();
currentHeight = ininitalHeight;
firstIteration = false;
} else {
currentHeight = $(mirror).height();
}
// Assume that textarea.rows = 2 initially
currentRow = currentHeight/(ininitalHeight/2) - 1;
//remove tracker in production
$('.tracker').html('Current row: ' + currentRow);
}
// Create a mirror
var mirror = createMirror(this);
// Style the mirror
mirror.style.display = 'none';
mirror.style.wordWrap = 'break-word';
mirror.style.whiteSpace = 'normal';
mirror.style.padding = jQuery(this).css('padding');
mirror.style.width = jQuery(this).css('width');
mirror.style.fontFamily = jQuery(this).css('font-family');
mirror.style.fontSize = jQuery(this).css('font-size');
mirror.style.lineHeight = jQuery(this).css('line-height');
// Style the textarea
this.style.overflow = "hidden";
this.style.minHeight = this.rows+"em";
var ininitalHeight = $(mirror).height();
// Bind the textarea's event
this.onkeyup = growTextarea;
// Fire the event for text already present
// sendContentToMirror(this);
});
};
$(function(){
$('textarea').trackRows();
});

This worked for me:
function getLineNumber(textarea) {
return textarea.value.substr(0, textarea.selectionStart) // get the substring of the textarea's value up to the cursor position
.split("\n") // split on explicit line breaks
.map((line) => 1 + Math.floor(line.length / textarea.cols)) // count the number of line wraps for each split and add 1 for the explicit line break
.reduce((a, b) => a + b, 0); // add all of these together
};
Inspired by colab's answer as a starting point, this includes the number of word wraps without having to introduce a mirror (as in bradbarbin's answer).
The trick is simply counting how many times the number of columns textarea.cols can divide the length of each segment between explicit line breaks \n.
Note: this starts counting at 1.

Make lines of text have equal length

In centered h1 elements, if the text falls on multiple lines, line breaks make the text look like this:
This is a header that takes up two
lines
This is a header that takes up three
lines because it is really, really
long
Is there a way to manipulate these elements so that the length of the lines of text is roughly equal? Like this:
This is a header that
takes up two lines
This is a header that takes
up three lines because it
is really, really long
The jQuery plugin Widow Fix prevents single-word lines, but I'm looking for something that evens out all the lines in a multi-line element. Are there any jQuery plugins for this, or can you recommend a strategy?

I would solve it using only strict JavaScript, going this way:
1. put a class named 'truncate' to h1 tags you want to break
2. configure the javascript code on your needs knowing that
MAXCOUNT: (integer) max chars counted per line
COUNT_SPACES: (boolean) white spaces must be counted?
COUNT_PUNCTUATION: (boolean) punctuation must be counted?
EXACT: (boolean) the last word must be cut?
BLOCKS_CLASS: (string) the className of the h1 to consider
I wrote the code very quickly so it must be better tested for bugs,
but it can be a starting point I think.
I'm not using jQuery in this code to keep the code light and to avoid dependencies.
I think I'm using all cross-browser commands (cannot test it I've got only linux now). However any correction for cross-browser compatibility task (included the use of jQUery if requested) might be easy.
Here is the code:
<html>
<head>
<style>
h1 {background-color: yellow;}
#hiddenDiv {background-color: yellow; display: table-cell; visibility:hidden;}
</style>
<script>
var MAXCOUNT = 20;
var COUNT_SPACES = false;
var EXACT = false;
var COUNT_PUNCTUATION = true;
var BLOCKS_CLASS = 'truncate';
window.onload = function ()
{
var hidden = document.getElementById('hiddenDiv');
if (hidden == null)
{
hidden = document.createElement('div');
hidden.id = 'hiddenDiv';
document.body.appendChild(hidden);
}
var blocks = document.getElementsByClassName(BLOCKS_CLASS);
for (var i=0; i<blocks.length; i++)
{
var block = blocks[i];
var text = block.innerHTML;
var truncate = '';
var html_tag = false;
var special_char = false;
maxcount = MAXCOUNT;
for (var x=0; x<maxcount; x++)
{
var previous_char = (x>0) ? text.charAt(x-1) : '';
var current_char = text.charAt(x);
// Closing HTML tags
if (current_char == '>' && html_tag)
{
html_tag = false;
maxcount++;
continue;
}
// Closing special chars
if (current_char == ';' && special_char)
{
special_char = false;
maxcount++;
continue;
}
// Jumping HTML tags
if (html_tag)
{
maxcount++;
continue;
}
// Jumping special chars
if (special_char)
{
maxcount++;
continue;
}
// Checking for HTML tags
if (current_char == '<')
{
var next = text.substring(x,text.indexOf('>')+1);
var regex = /(^<\w+[^>]*>$)/gi;
var matches = regex.exec(next);
if (matches[0])
{
html_tag = true;
maxcount++;
continue;
}
}
// Checking for special chars
if (current_char == '&')
{
var next = text.substring(x,text.indexOf(';')+1);
var regex = /(^&#{0,1}[0-9a-z]+;$)/gi;
var matches = regex.exec(next);
if (matches[0])
{
special_char = true;
maxcount++;
continue;
}
}
// Shrink multiple white spaces into a single white space
if (current_char == ' ' && previous_char == ' ')
{
maxcount++;
continue;
}
// Jump new lines
if (current_char.match(/\n/))
{
maxcount++;
continue;
}
if (current_char == ' ')
{
// End of the last word
if (x == maxcount-1 && !EXACT) { break; }
// Must I count white spaces?
if ( !COUNT_SPACES ) { maxcount++; }
}
// Must I count punctuation?
if (current_char.match(/\W/) && current_char != ' ' && !COUNT_PUNCTUATION)
{
maxcount++;
}
// Adding this char
truncate += current_char;
// Must I cut exactly?
if (!EXACT && x == maxcount-1) { maxcount++; }
}
hidden.innerHTML = '<h1><nobr>'+truncate+'</nobr></h1>';
block.style.width = hidden.offsetWidth+"px";
}
}
</script>
</head>
<body>
<center>
<h1 class="truncate">
This is a header that
takes up two lines
</h1>
<br>
<h1 class="truncate">
This is a header that takes
up three lines because it
is really, really long
</h1>
<br>
<h1>
This is a header pretty short
or pretty long ... still undecided
which in any case is not truncated!
</h1>
</center>
</body>
</html>
And here is a demo of that: http://jsfiddle.net/6rtdF/

Late to this party, but here's my approach. I get the initial element height (any elements with the class balance_lines, in the code below), then incrementally shrink the width of the element. Once the height of the element changes, I've gone too far. The step before that should have lovely roughly-equal line lengths.
$('.balance_lines').each(function(){
var currentHeight = $(this).height();
var thisHeight = currentHeight;
var currentWidth = $(this).width();
var newWidth = currentWidth;
// Try shrinking width until height changes
while (thisHeight == currentHeight) {
var testWidth = newWidth - 10;
$(this).width(testWidth);
thisHeight = $(this).height();
if (thisHeight == currentHeight) {
newWidth = testWidth;
} else {
break;
}
}
$(this).width(newWidth);
});
You can see this code in action on the homepage at apollopad.com.

The CSS Text 4 draft proposes text-wrap: balance, but I don't think any browser implements it yet.
In the meantime, you can use Adobe's jQuery plugin (demo): https://github.com/adobe-webplatform/balance-text

Javascript Limit Commas

I have a function that displays a countdown next to a text field for the number of characters in the field (think twitter)
<script language="javascript" type="text/javascript">
function countDown(control, maxLen, counter, typeName) {
var len = control.value.length;
var txt = control.value;
var span = document.getElementById(counter);
span.style.display = '';
span.innerHTML = (maxLen - len);
if (len >= (maxLen - 10)) {
span.style.color = 'red';
} else {
span.style.color = '';
}
}
</script>
And the next field down takes a comma separated value. Example:
tomato, apple, orange, pear
and I'd like to limit that list to 5 things (and 4 separating commas).
How can I make a similar function that counts down for the number of commas in the input.
I got this started, but it's not changing the value in the span.
my Javascript
<script language="javascript" type="text/javascript">
var max = 5;
function commaDown(area,ticker){
// our text in the textarea element
var txt = area.val();
// how many commas we have?
var commas = txt.split(",").length;
var span = document.getElementById(ticker);
//var commas ++;
if(commas > max) {
// grab last comma position
var lastComma = txt.lastIndexOf(",");
// delete all after last comma position
area.val(txt.substring(0, lastComma));
//it was count with + 1, so let's take that down
commas--;
}
if (txt == '') {
commas = 0;
}
// show message
span.innerHTML = (max-commas);
}
</script>
and my html (I think the problem lies here)
<input id="choices" type="text" name="choices" class="text medium" onkeyup="commaDown('choices','limit');"/> <span id="limit">5</span><br/>
Any ideas?

Something like this (assuming you have a text field with id csv)
document.getElementById('csv').onkeydown = function(e){
if (!e) var e = window.event;
var list = this.value.split(',');
if (list.length == 5 && e.keyCode == '188' )
{
// what to do if more than 5 commas(,) are entered
// i put a red border and make it go after 1 second
this.style.borderColor ='red';
var _this = this;
setTimeout(function(){
_this.style.borderColor='';
_this.disabled=false;
},1000);
// return false to forbid the surplus comma to be entered in the field
return false;
}
}
example at http://www.jsfiddle.net/gaby/YEHXf/2/
Updated Answer
You seem to have mixed parts of jQuery in your code and that causes the script to fail
var max = 5;
function commaDown(_area, _ticker){
var area = document.getElementById(_area);
// our text in the textarea element
var txt = area.value;
// how many commas we have?
var commas = txt.split(",").length;
var span = document.getElementById(_ticker);
//var commas ++;
if(commas > max) {
// grab last comma position
var lastComma = txt.lastIndexOf(",");
// delete all after last comma position
area.value = txt.substring(0, lastComma);
//it was count with + 1, so let's take that down
commas--;
}
if (txt == '') {
commas = 0;
}
// show message
span.innerHTML = (max-commas);
}
live example at http://jsfiddle.net/z4KRd/

here is a solution:
test: http://jsbin.com/ulobu3
code: http://jsbin.com/ulobu3/edit
if you never used jsBin before, it is very easy, on the left side you have the javascript code (like if it was in your HTML code, and in your right side you have the html code.
and you just need to add /edit to the end of a jsbin url to edit that code, and save any new revisions to that code.
I added jQuery framework to make the example faster to code.