I have a div that acts as a WYSIWYG editor. This acts as a text box but renders markdown syntax within it, to show live changes.
Problem: When a letter is typed, the caret position is reset to the start of the div.
const editor = document.querySelector('div');
editor.innerHTML = parse('**dlob** *cilati*');
editor.addEventListener('input', () => {
editor.innerHTML = parse(editor.innerText);
});
function parse(text) {
return text
.replace(/\*\*(.*)\*\*/gm, '**<strong>$1</strong>**') // bold
.replace(/\*(.*)\*/gm, '*<em>$1</em>*'); // italic
}
div {
height: 100vh;
width: 100vw;
}
<div contenteditable />
Codepen: https://codepen.io/ADAMJR/pen/MWvPebK
Markdown editors like QuillJS seem to edit child elements without editing the parent element. This avoids the problem but I'm now sure how to recreate that logic with this setup.
Question: How would I get the caret position to not reset when typing?
Update:
I have managed to send the caret position to the end of the div, on each input. However, this still essentially resets the position. https://codepen.io/ADAMJR/pen/KKvGNbY
You need to get position of the cursor first then process and set the content. Then restore the cursor position.
Restoring cursor position is a tricky part when there are nested elements. Also you are creating new <strong> and <em> elements every time, old ones are being discarded.
const editor = document.querySelector(".editor");
editor.innerHTML = parse(
"For **bold** two stars.\nFor *italic* one star. Some more **bold**."
);
editor.addEventListener("input", () => {
//get current cursor position
const sel = window.getSelection();
const node = sel.focusNode;
const offset = sel.focusOffset;
const pos = getCursorPosition(editor, node, offset, { pos: 0, done: false });
if (offset === 0) pos.pos += 0.5;
editor.innerHTML = parse(editor.innerText);
// restore the position
sel.removeAllRanges();
const range = setCursorPosition(editor, document.createRange(), {
pos: pos.pos,
done: false,
});
range.collapse(true);
sel.addRange(range);
});
function parse(text) {
//use (.*?) lazy quantifiers to match content inside
return (
text
.replace(/\*{2}(.*?)\*{2}/gm, "**<strong>$1</strong>**") // bold
.replace(/(?<!\*)\*(?!\*)(.*?)(?<!\*)\*(?!\*)/gm, "*<em>$1</em>*") // italic
// handle special characters
.replace(/\n/gm, "<br>")
.replace(/\t/gm, " ")
);
}
// get the cursor position from .editor start
function getCursorPosition(parent, node, offset, stat) {
if (stat.done) return stat;
let currentNode = null;
if (parent.childNodes.length == 0) {
stat.pos += parent.textContent.length;
} else {
for (let i = 0; i < parent.childNodes.length && !stat.done; i++) {
currentNode = parent.childNodes[i];
if (currentNode === node) {
stat.pos += offset;
stat.done = true;
return stat;
} else getCursorPosition(currentNode, node, offset, stat);
}
}
return stat;
}
//find the child node and relative position and set it on range
function setCursorPosition(parent, range, stat) {
if (stat.done) return range;
if (parent.childNodes.length == 0) {
if (parent.textContent.length >= stat.pos) {
range.setStart(parent, stat.pos);
stat.done = true;
} else {
stat.pos = stat.pos - parent.textContent.length;
}
} else {
for (let i = 0; i < parent.childNodes.length && !stat.done; i++) {
currentNode = parent.childNodes[i];
setCursorPosition(currentNode, range, stat);
}
}
return range;
}
.editor {
height: 100px;
width: 400px;
border: 1px solid #888;
padding: 0.5rem;
white-space: pre;
}
em, strong{
font-size: 1.3rem;
}
<div class="editor" contenteditable ></div>
The API window.getSelection returns Node and position relative to it. Every time you are creating brand new elements so we can't restore position using old node objects. So to keep it simple and have more control, we are getting position relative to the .editor using getCursorPosition function. And, after we set innerHTML content we restore the cursor position using setCursorPosition.
Both functions work with nested elements.
Also, improved the regular expressions: used (.*?) lazy quantifiers and lookahead and behind for better matching. You can find better expressions.
Note:
I've tested the code on Chrome 97 on Windows 10.
Used recursive solution in getCursorPosition and setCursorPosition for the demo and to keep it simple.
Special characters like newline require conversion to their equivalent HTML form, e.g. <br>. Tab characters require white-space: pre set on the editable element. I've tried to handled \n, \t in the demo.
The way most rich text editors does it is by keeping their own internal state, updating it on key down events and rendering a custom visual layer. For example like this:
const $editor = document.querySelector('.editor');
const state = {
cursorPosition: 0,
contents: 'hello world'.split(''),
isFocused: false,
};
const $cursor = document.createElement('span');
$cursor.classList.add('cursor');
$cursor.innerText = ''; // Mongolian vowel separator
const renderEditor = () => {
const $contents = state.contents
.map(char => {
const $span = document.createElement('span');
$span.innerText = char;
return $span;
});
$contents.splice(state.cursorPosition, 0, $cursor);
$editor.innerHTML = '';
$contents.forEach(el => $editor.append(el));
}
document.addEventListener('click', (ev) => {
if (ev.target === $editor) {
$editor.classList.add('focus');
state.isFocused = true;
} else {
$editor.classList.remove('focus');
state.isFocused = false;
}
});
document.addEventListener('keydown', (ev) => {
if (!state.isFocused) return;
switch(ev.key) {
case 'ArrowRight':
state.cursorPosition = Math.min(
state.contents.length,
state.cursorPosition + 1
);
renderEditor();
return;
case 'ArrowLeft':
state.cursorPosition = Math.max(
0,
state.cursorPosition - 1
);
renderEditor();
return;
case 'Backspace':
if (state.cursorPosition === 0) return;
delete state.contents[state.cursorPosition-1];
state.contents = state.contents.filter(Boolean);
state.cursorPosition = Math.max(
0,
state.cursorPosition - 1
);
renderEditor();
return;
default:
// This is very naive
if (ev.key.length > 1) return;
state.contents.splice(state.cursorPosition, 0, ev.key);
state.cursorPosition += 1;
renderEditor();
return;
}
});
renderEditor();
.editor {
position: relative;
min-height: 100px;
max-height: max-content;
width: 100%;
border: black 1px solid;
}
.editor.focus {
border-color: blue;
}
.editor.focus .cursor {
position: absolute;
border: black solid 1px;
border-top: 0;
border-bottom: 0;
animation-name: blink;
animation-duration: 1s;
animation-iteration-count: infinite;
}
#keyframes blink {
from {opacity: 0;}
50% {opacity: 1;}
to {opacity: 0;}
}
<div class="editor"></div>
You need to keep the state of the position and restore it on each input. There is no other way. You can look at how content editable is handled in my project jQuery Terminal (the links point to specific lines in source code and use commit hash, current master when I've written this, so they will always point to those lines).
insert method that is used when user type something (or on copy-paste).
fix_textarea - the function didn't changed after I've added content editable. The function makes sure that textarea or contenteditable (that are hidden) have the same state as the visible cursor.
clip object (that is textarea or content editable - another not refactored name that in beginning was only for clipboard).
For position I use jQuery Caret that is the core of moving the cursor. You can easily modify this code and make it work as you want. jQuery plugin can be easily refactored into a function move_cursor.
This should give you an idea how to implement this on your own in your project.
You can use window.getSelection to get the current position and, after parsing, move the cursor to again this position with sel.modify.
const editor = document.querySelector('div')
editor.innerHTML = parse('**dlob** *cilati*')
sel = window.getSelection()
editor.addEventListener('input', () => {
sel.extend(editor, 0)
pos = sel.toString().length
editor.innerHTML = parse(editor.innerText)
while (pos-->0)
sel.modify('move', 'forward', "character")
})
function parse(text) {
return text
.replace(/\*\*(.*)\*\*/gm, '**<strong>$1</strong>**') // bold
.replace(/\*(.*)\*/gm, '*<em>$1</em>*'); // italic
}
div {
height: 100vh;
width: 100vw;
}
<div contenteditable />
That said, note the edit history is gone (i.e. no undo), when using editor.innerHTML = ....
As other indicated, it seems better to separate editing and rendering.
I call this pseudo-contenteditable. I asked a question related to this
Pseudo contenteditable: how does codemirror works?. Still waiting for an answer.
But the basic idea might look this https://jsfiddle.net/Lfbt4c7p.
I came across this Stack Overflow post where was discussed the exact thing I needed: to be able to paste text into a contenteditable area, retaining only a few styles. I ran the code snippet there and it work fine. However, when I tried it on my page, all styles were being removed, including those I wanted to keep, like bold and italic. After comparing the codes and a few experimentations, I realized that the reason it was not working was because I was using external CSS, instead of inline.
Is there any way I can make it work with external CSS? I will never know the origin of the text users will post in that contenteditable, and how was style applied to it, so I am looking to address all possibilities.
Also, is there a way to make it work with dragged and dropped text, instead of just pasted text? I tried replacing the event it is listening to from "paste" to "drop", but I get the error e.clipboardData is undefined
const el = document.querySelector('p');
el.addEventListener('paste', (e) => {
// Get user's pasted data
let data = e.clipboardData.getData('text/html') ||
e.clipboardData.getData('text/plain');
// Filter out everything except simple text and allowable HTML elements
let regex = /<(?!(\/\s*)?(b|i|em|strong|u)[>,\s])([^>])*>/g;
data = data.replace(regex, '');
// Insert the filtered content
document.execCommand('insertHTML', false, data);
// Prevent the standard paste behavior
e.preventDefault();
});
.editable {
width: 100%;
min-height: 20px;
font-size: 14px;
color: black;
font-family: arial;
line-height: 1.5;
border: solid 1px black;
margin-bottom: 30px;
}
.big {
font-size: 20px;
}
.red {
color: red;
}
.bold {
font-weight: bold;
}
.italic {
text-decoration: italic;
}
<p class="editable" contenteditable></p>
<p class="notEditable">
Try pasting this paragraph into the contenteditable paragraph above. This text includes <b>BOLD</b>, <i>ITALIC</i>, <s>STRIKE</s>, <u>UNDERLINE</u>, a <a href='#'>LINK</a>, and <span style="font-size:30px; color:red; font-family:Times New Roman">a few other styles.</span> All styles are inline, and it works as expected.
</p>
<p>Now, try pasting this paragraph with external styles. <span class="big">Big</span > <span class="red">red</span> <span class="bold">bold</span> <span class="italic">italic</span>. It no longer works.</p>
As other answer pointed out I don't know any way of getting CSS styles out of other pages using clipboard. . But at your own you could do something like this:
Get getComputedStyle (CSS only) of all elements filter out wanted style, in this example fontStyle and fontWeight. Then you can condition if fontStyle==="italic" or fontweight==="700" (bold), textDecoration==="underline rgb(0, 0, 0)" and wrap that elements into its HTML tags.
You do this because your regex function is only targeting tags, not even inline CSS property font-style: italic;. Witch is a shame, it would make things a bit easier as you could just read every elements CSS class style and apply it inline, but this way you need to condition it and apply HTML tag.
if ( style.fontStyle==="italic"){
element.innerHTML = "<i>" + element.innerHTML + "</i>";
;}
if ( style.fontWeight==="700"){
element.innerHTML = "<b>" + element.innerHTML + "</b>";
;}
if (style.textDecoration==="underline rgb(0, 0, 0)"){
element.innerHTML = "<u>" + element.innerHTML + "</u>";
;}
In example below if you copy Now, try pasting this paragraph with external styles. Big red bold italic. It no longer works. you will get bold,underline and italic. You can do the same for rest of your filtering options.
const el = document.querySelector('p');
el.addEventListener('paste', (e) => {
// Get user's pasted data
let data = e.clipboardData.getData('text/html') ||
e.clipboardData.getData('text/plain');
//console.log(data)
// Filter out everything except simple text and allowable HTML elements
let regex = /<(?!(\/\s*)?(b|i|em|strong|u)[>,\s])([^>])*>/g;
data = data.replace(regex, '');
//console.log(data)
// Insert the filtered content
document.execCommand('insertHTML', false, data);
// Prevent the standard paste behavior
e.preventDefault();
});
[...document.querySelectorAll('body *')].forEach(element=>{
const style = getComputedStyle(element)
if ( style.fontStyle==="italic"){
element.innerHTML = "<i>" + element.innerHTML + "</i>";
;}
if ( style.fontWeight==="700"){
element.innerHTML = "<b>" + element.innerHTML + "</b>";
;}
if (style.textDecoration==="underline rgb(0, 0, 0)"){
element.innerHTML = "<u>" + element.innerHTML + "</u>";
;}
});
.editable {
width: 100%;
min-height: 20px;
font-size: 14px;
color: black;
font-family: arial;
line-height: 1.5;
border: solid 1px black;
margin-bottom: 30px;
}
.big {
font-size: 20px;
}
.red {
color: red;
}
.bold {
font-weight: bold;
}
.underline{
text-decoration: underline;
}
.italic {
font-style: italic;
}
<p class="editable" contenteditable></p>
<p class="notEditable">
Try pasting this paragraph into the contenteditable paragraph above. This text includes <b>BOLD</b>, <i>ITALIC</i>, <s>STRIKE</s>, <u>UNDERLINE</u>, a <a href='#'>LINK</a>, and <span style="font-size:30px; color:red; font-family:Times New Roman">a few other styles.</span> All styles are inline, and it works as expected.
</p>
<p id="container"><span class="underline">Now</span>, try pasting this paragraph with external styles. <span class="big">Big</span > <span class="red">red</span> <span class="bold" >bold</span> <span class="italic">italic</span>. It no longer works.</p>
Unfortunately, there is no way to keep the properties of a class from an external source. If you would print the content of the clipboard, you will see that you receive the raw HTML content as it is on the external page, for example:
<div class="some-class">this is the text</div>
The class properties would not be inlined by the browser! And as the content is from an external source, you have no power over it.
On the other hand, if the content is from your page (so the class is defined), you could parse the received HTML and filter the CSS properties, keeping only what you want. Here you have a code sample using vanilla Javascript, no libraries required (also available on Codepen):
const targetEditable = document.querySelector('p');
targetEditable.addEventListener('paste', (event) => {
let data = event.clipboardData.getData('text/html') ||
event.clipboardData.getData('text/plain');
// Filter the string using your already existing rules
// But allow <p> and <div>
let regex = /<(?!(\/\s*)?(div|b|i|em|strong|u|p)[>,\s])([^>])*>/g;
data = data.replace(regex, '');
const newElement = createElementFromHTMLString(data);
const cssContent = generateFilteredCSS(newElement);
addCssToDocument(cssContent);
document.execCommand('insertHTML', false, newElement.innerHTML);
event.preventDefault();
});
// Scan the HTML elements recursively and generate CSS classes containing only the allowed properties
function generateFilteredCSS(node) {
const newClassName = randomString(5);
let content = `.${newClassName}{\n`;
if (node.className !== undefined && node.className !== '') {
// Get an element that has the class
const elemOfClass = document.getElementsByClassName(node.className)[0];
// Get the computed style properties
const styles = window.getComputedStyle(elemOfClass);
// Properties whitelist, keep only those
const propertiesToKeep = ['font-weight'];
for (const property of propertiesToKeep) {
content += `${property}: ${styles.getPropertyValue(property)};\n`;
}
}
content += '}\n';
node.className = newClassName;
for (const child of node.childNodes) {
content += generateFilteredCSS(child);
}
return content;
}
function createElementFromHTMLString(htmlString) {
var div = document.createElement('div');
div.innerHTML = htmlString.trim();
return div;
}
function addCssToDocument(cssContent) {
var element = document.createElement("style");
element.innerHTML = cssContent;
var header = document.getElementsByTagName("HEAD")[0];
header.appendChild(element);
}
function randomString(length) {
var result = '';
var characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
var charactersLength = characters.length;
for (var i = 0; i < length; i++) {
result += characters.charAt(Math.floor(Math.random() * charactersLength));
}
return result;
}
.editable {
width: 100%;
min-height: 20px;
font-size: 14px;
color: black;
font-family: arial;
line-height: 1.5;
border: solid 1px black;
margin-bottom: 30px;
}
.red-bg {
background-color: red;
font-weight: bold;
}
<p class="editable" contenteditable></p>
<p class="red-bg test">
This is some text
</p>
About the drag and drop functionality, you have to use event.dataTransfer.getData() in the drop event listener, the rest is the same.
References
How to generate a DOM element from a HTML string
How to add CSS classes at runtime using Javascript
How to generate a random string (unique ID) in Javascript
Drag&drop data transfer
You could accomplish what you want, but would require an additional set of considerations.
First you add an "Add Source Assets" button, which the user would supply the source page URL... Then you would fetch the source HTML and match the pasted content, with the source content, then interrogate the source elements for all related attributes, referenced classes etc.
You could even process the source URL's markup to extract it's css and images as references... Essentially onboarding the resources based on a whitelist of acceptable media and styles.
Depending on your needs and DOM Kung Fu, you could extract all "consumed" css and import those styles... It really depends how far you want to go.
<input type="text" value="1" style="min-width:1px;" />
This is my code and it is not working. Is there any other way in HTML, JavaScript, PHP or CSS to set minimum width?
I want a text input field with a dynamically changing width, so that the input field fluids around its contents. Every input has a built-in padding of 2em, that is the problem and second problem is that min-width ain't working on input at all.
If I set width more than it is needed than the whole program is messy, I need the width of 1px, more only if it's needed.
In modern browser versions, CSS unit ch is also available. To my understanding, it is font-independent unit, where 1ch equals to width of character 0 (zero) in any given font.
Thus, something as simple as following could be used as resize function, by binding to the input event:
var input = document.querySelector('input'); // get the input element
input.addEventListener('input', resizeInput); // bind the "resizeInput" callback on "input" event
resizeInput.call(input); // immediately call the function
function resizeInput() {
this.style.width = this.value.length + "ch";
}
input{ font-size:1.3em; padding:.5em; }
<label>Text
<input>
</label>
That example would resize the input to length of the value + 2 characters extra.
One potential problem with the unit ch is that in many fonts (i.e. Helvetica) the width of the character "m" exceeds the width of the character 0 and the character "i" is much narrower. 1ch is usually wider than the average character width, usually by around 20-30% according to this post.
It sounds like your expectation is that the style be applied dynamically to the width of the textbox based on the contents of the textbox. If so you will need some js to run on textbox contents changing, something like this:
<input id="txt" type="text" onkeypress="this.style.width = ((this.value.length + 1) * 8) + 'px';">
Note: this solution only works when every character is exactly 8px wide. You could use the CSS-Unit "ch" (characters) which represents the width of the character "0" in the chosen font. You can read about it here.
To calculate the width of the current input, you'll have to embed it in a temporary span element, attach that thing to the DOM, get the computed width (in pixels) using the scrollWidth property and remove the span again. Of course you'll have to ensure that the same font family, font size, etc., is used in the input as well as in the span element. Therefore I assigned the same class to them.
I attached the function to the keyup event, as on keypress the input character is not yet added to the input value, so that will result in the wrong width. Unfortunately, I don't know how to get rid of the scrolling of the input field (when adding characters to the end of the field); it scrolls, because the character is added and shown before adjustWidthOfInput() is called. And, as said, I can't do this the other way round because then you'll have the value of the input field before the pressed character is inserted. I'll try to solve this issue later.
BTW, I only tested this in Firefox (3.6.8), but you'll get the point, I hope.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Get/set width of <input></title>
<style>
body {
background: #666;
}
.input-element {
border: 0;
padding: 2px;
background: #fff;
font: 12pt sans-serif;
}
.tmp-element {
visibility: hidden;
white-space: pre;
}
</style>
</head>
<body>
<input id="theInput" type="text" class="input-element" value="1">
<script>
var inputEl = document.getElementById("theInput");
function getWidthOfInput() {
var tmp = document.createElement("span");
tmp.className = "input-element tmp-element";
tmp.innerHTML = inputEl.value.replace(/&/g,'&').replace(/</g,'<').replace(/>/g,'>');
document.body.appendChild(tmp);
var theWidth = tmp.getBoundingClientRect().width;
document.body.removeChild(tmp);
return theWidth;
}
function adjustWidthOfInput() {
inputEl.style.width = getWidthOfInput() + "px";
}
adjustWidthOfInput();
inputEl.onkeyup = adjustWidthOfInput;
</script>
</body>
</html>
Here is a solution without monospaced font needed, with only a very small piece code of javascript, does not need to calculate computed styles, and even supports IME, supports RTL text.
// copy the text from input to the span
$(function () {
$('.input').on('input', function () { $('.text').text($('.input').val()); });
});
* {
box-sizing: border-box;
}
.container {
display: inline-block;
position: relative;
}
.input,
.text {
margin: 0;
padding: 2px 10px;
font-size: 24px;
line-height: 32px;
border: 1px solid #ccc;
box-radius: 3px;
height: 36px;
font: 20px/20px sans-serif;
/* font: they should use same font; */
}
.text {
padding-right: 20px;
display: inline-block;
visibility: hidden;
white-space: pre;
}
.input {
position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;
width: 100%;
}
<script src="https://code.jquery.com/jquery-3.2.0.min.js"></script>
<div class="container">
<span class="text">
some text
</span>
<input class="input" value="some text" />
</div>
Use the span.text to fit width of text, and let the input have same size with it by position: absolute to the container. Copy value of input to the span every time it changes (you may change this piece of code to vanilla JS easily, or use features provided by your frontend framework). So the input will just fit the size of its content.
Here's a modification of Lyth's answer that takes into account:
Deletion
Initialisation
Placeholders
It also allows for any number of input fields! To see it in action: http://jsfiddle.net/4Qsa8/
Script:
$(document).ready(function () {
var $inputs = $('.resizing-input');
// Resize based on text if text.length > 0
// Otherwise resize based on the placeholder
function resizeForText(text) {
var $this = $(this);
if (!text.trim()) {
text = $this.attr('placeholder').trim();
}
var $span = $this.parent().find('span');
$span.text(text);
var $inputSize = $span.width();
$this.css("width", $inputSize);
}
$inputs.find('input').keypress(function (e) {
if (e.which && e.charCode) {
var c = String.fromCharCode(e.keyCode | e.charCode);
var $this = $(this);
resizeForText.call($this, $this.val() + c);
}
});
// Backspace event only fires for keyup
$inputs.find('input').keyup(function (e) {
if (e.keyCode === 8 || e.keyCode === 46) {
resizeForText.call($(this), $(this).val());
}
});
$inputs.find('input').each(function () {
var $this = $(this);
resizeForText.call($this, $this.val())
});
});
Style:
.resizing-input input, .resizing-input span {
font-size: 12px;
font-family: Sans-serif;
white-space: pre;
padding: 5px;
}
HTML:
<div class="resizing-input">
<input type="text" placeholder="placeholder"/>
<span style="display:none"></span>
</div>
$(document).ready(function() {
var $inputs = $('.resizing-input');
// Resize based on text if text.length > 0
// Otherwise resize based on the placeholder
function resizeForText(text) {
var $this = $(this);
if (!text.trim()) {
text = $this.attr('placeholder').trim();
}
var $span = $this.parent().find('span');
$span.text(text);
var $inputSize = $span.width();
$this.css("width", $inputSize);
}
$inputs.find('input').keypress(function(e) {
if (e.which && e.charCode) {
var c = String.fromCharCode(e.keyCode | e.charCode);
var $this = $(this);
resizeForText.call($this, $this.val() + c);
}
});
// Backspace event only fires for keyup
$inputs.find('input').keyup(function(e) {
if (e.keyCode === 8 || e.keyCode === 46) {
resizeForText.call($(this), $(this).val());
}
});
$inputs.find('input').each(function() {
var $this = $(this);
resizeForText.call($this, $this.val())
});
});
.resizing-input input,
.resizing-input span {
font-size: 12px;
font-family: Sans-serif;
white-space: pre;
padding: 5px;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.0/jquery.min.js"></script>
<div class="resizing-input">
First:
<input type="text" placeholder="placeholder" />
<span style="display:none"></span>
</div>
<br>
This is an Angular-specific answer, but this worked for me and has been very satisfying in terms of its simplicity and ease-of-use:
<input [style.width.ch]="value.length" [(ngModel)]="value" />
It automatically updates via the character units in Jani's answer.
FOR A NICER LOOK&FEEL
You should use jQuery keypress() event in combination with String.fromCharCode(e.which) to get the pressed character. Hence you can calculate what your width will be. Why? Because it will look a lot more sexy :)
Here is a jsfiddle that results in a nice behaviour compared to solutions using the keyup event : http://jsfiddle.net/G4FKW/3/
Below is a vanilla JS which listens to the input event of an <input> element and sets a span sibling to have the same text value in order to measure it.
document.querySelector('input').addEventListener('input', onInput)
function onInput(){
var spanElm = this.nextElementSibling;
spanElm.textContent = this.value; // the hidden span takes the value of the input;
this.style.width = spanElm.offsetWidth + 'px'; // apply width of the span to the input
};
/* it's important the input and its span have same styling */
input, .measure {
padding: 5px;
font-size: 2.3rem;
font-family: Sans-serif;
white-space: pre; /* white-spaces will work effectively */
}
.measure{
position: absolute;
left: -9999px;
top: -9999px;
}
<input type="text" />
<span class='measure'></span>
Here is an alternative way to solve this using a DIV and the 'contenteditable' property:
HTML:
<div contenteditable = "true" class = "fluidInput" data-placeholder = ""></div>
CSS: (to give the DIV some dimensions and make it easier to see)
.fluidInput {
display : inline-block;
vertical-align : top;
min-width : 1em;
height : 1.5em;
font-family : Arial, Helvetica, sans-serif;
font-size : 0.8em;
line-height : 1.5em;
padding : 0px 2px 0px 2px;
border : 1px solid #aaa;
cursor : text;
}
.fluidInput * {
display : inline;
}
.fluidInput br {
display : none;
}
.fluidInput:empty:before {
content : attr(data-placeholder);
color : #ccc;
}
Note: If you are planning on using this inside of a FORM element that you plan to submit, you will need to use Javascript / jQuery to catch the submit event so that you can parse the 'value' ( .innerHTML or .html() respectively) of the DIV.
Just adding on top of other answers.
I noticed that nowadays in some browsers the input field has a scrollWidth. Which means:
this.style.width = this.scrollWidth + 'px';
should work nicely. tested in chrome, firefox and safari.
For deletion support, you can add '=0' first and then readjust.
this.style.width = 0; this.style.width = this.scrollWidth + 'px';
This answer provides one of the most accurate methods of retrieving text width available in the browser and is more accurate than the accepted answer. It uses the canvas html5 element and unlike other answers does not add the element into the DOM and thus avoids any reflow issues caused by excessively adding elements to the DOM.
Read more about the Canvas element here in relation to text width.
NOTE: According to MDN the shorthand versions of the getPropertyValue() method such as font can be unreliable. I'd recommend getting the values singularly to improve compatibility. I only used it here for speed.
/**
* returns the width of child text of any DOM node as a float
*/
function getTextWidth(el) {
// uses a cached canvas if available
var canvas = getTextWidth.canvas || (getTextWidth.canvas = document.createElement("canvas"));
var context = canvas.getContext("2d");
// get the full font style property
var font = window.getComputedStyle(el, null).getPropertyValue('font');
var text = el.value;
// set the font attr for the canvas text
context.font = font;
var textMeasurement = context.measureText(text);
return textMeasurement.width;
}
var input = document.getElementById('myInput');
// listen for any input on the input field
input.addEventListener('input', function(e) {
var width = Math.floor(getTextWidth(e.target));
// add 10 px to pad the input.
var widthInPx = (width + 10) + "px";
e.target.style.width = widthInPx;
}, false);
#myInput {
font: normal normal 400 normal 18px / normal Roboto, sans-serif;
min-width: 40px;
}
<input id="myInput" />
You can set an input's width using the size attribute as well. The size of an input determines it's width in characters.
An input could dynamically adjust it's size by listening for key events.
For example
$("input[type='text']").bind('keyup', function () {
$(this).attr("size", $(this).val().length );
});
JsFiddle here
You could do something like this
// HTML
<input id="input" type="text" style="width:3px" />
// jQuery
$(function(){
$('#input').keyup(function(){
$('<span id="width">').append( $(this).val() ).appendTo('body');
$(this).width( $('#width').width() + 2 );
$('#width').remove();
});
});
You can just set size attribute.
If you're using one of reactive frameworks, the following will be enough:
<input size="{{ yourValue.length }}" [value]="yourValue" />
but if you're using pure js, you should set event handlers, like:
<input oninput="this.setAttribute('size', this.value.length)" />
It's worth noting that a nice-looking resize can be done when the font is monospaced, so we can perfectly resize the input element using the ch unit.
Also in this approach we can update the width of the field by just updating a CSS variable (custom property) on input event and we should also take care of already pre-filled input on DOMContentLoaded event
Codepen demo
Markup
<input type="text" value="space mono font" class="selfadapt" />
CSS
:root { --size: 0; }
.selfadapt {
padding: 5px;
min-width: 10ch;
font-family: "space mono";
font-size: 1.5rem;
width: calc(var(--size) * 1ch);
}
As a root variable we set --size: 0: this variable will contain the length of the input and it will be multiplied by 1ch inside the calc() expression. By default we could also set a min-width, e.g. 10ch
The Javascript part reads the length of the value inserted and updates the variable --size:
JS
let input = document.querySelector('.selfadapt');
let root = document.documentElement.style;
/* on input event auto resize the field */
input.addEventListener('input', function() {
root.setProperty('--size', this.value.length );
});
/* resize the field if it is pre-populated */
document.addEventListener("DOMContentLoaded", function() {
root.setProperty('--size', input.value.length);
});
of course this still works even if you don't use monospaced font, but in that case you will need to change the calc() formula by multiplying the --size variable by another value (which it's strictly dependent on the font-family and font-size) different than 1ch.
Here is a plain JS and a jQuery plugin I wrote that will handle resizing an input element using a canvas and the font size / family to determine the actual string length when rendered. (only works in > IE9, chrome, safari, firefox, opera and most other major browsers that have implemented the canvas element).
PlainJS:
function autoSize(input, o) {
o || (o = {});
o.on || (o.on = 'keyup');
var canvas = document.createElement('canvas');
canvas.setAttribute('style', 'position: absolute; left: -9999px');
document.body.appendChild(canvas);
var ctx = canvas.getContext('2d');
input.addEventListener(o.on, function () {
ctx.font = getComputedStyle(this,null).getPropertyValue('font');
this.style.width = ctx.measureText(this.value + ' ').width + 'px';
});
}
//Usage
autoSize(document.getElementById('my-input'));
jQuery Plugin:
$.fn.autoSize = function(o) {
o = $.extend({}, {
on: 'keyup'
}, o);
var $canvas = $('<canvas/>').css({position: 'absolute', left: -9999});
$('body').append($canvas);
var ctx = $canvas[0].getContext('2d');
return this.on(o.on, function(){
var $this = $(this);
ctx.font = $this.css('font');
$this.width(ctx.measureText($this.val()).width + 'px');
})
}
//Usage:
$('#my-input').autoSize();
Note: this will not handle text-transforms, line spacing and letter spacing, and probably some other text size changing properties. To handle text-transform property set and adjust the text value to match that property. The others are probably fairly straight forward. I will implement if this starts gaining some traction...
A bullet-proof, generic way has to:
Take into account all possible styles of the measured input element
Be able to apply the measurement on any input without modifying the HTML or
Codepen demo
var getInputValueWidth = (function(){
// https://stackoverflow.com/a/49982135/104380
function copyNodeStyle(sourceNode, targetNode) {
var computedStyle = window.getComputedStyle(sourceNode);
Array.from(computedStyle).forEach(key => targetNode.style.setProperty(key, computedStyle.getPropertyValue(key), computedStyle.getPropertyPriority(key)))
}
function createInputMeassureElm( inputelm ){
// create a dummy input element for measurements
var meassureElm = document.createElement('span');
// copy the read input's styles to the dummy input
copyNodeStyle(inputelm, meassureElm);
// set hard-coded styles needed for propper meassuring
meassureElm.style.width = 'auto';
meassureElm.style.position = 'absolute';
meassureElm.style.left = '-9999px';
meassureElm.style.top = '-9999px';
meassureElm.style.whiteSpace = 'pre';
meassureElm.textContent = inputelm.value || '';
// add the meassure element to the body
document.body.appendChild(meassureElm);
return meassureElm;
}
return function(){
return createInputMeassureElm(this).offsetWidth;
}
})();
// delegated event binding
document.body.addEventListener('input', onInputDelegate)
function onInputDelegate(e){
if( e.target.classList.contains('autoSize') )
e.target.style.width = getInputValueWidth.call(e.target) + 'px';
}
input{
font-size:1.3em;
padding:5px;
margin-bottom: 1em;
}
input.type2{
font-size: 2.5em;
letter-spacing: 4px;
font-style: italic;
}
<input class='autoSize' value="type something">
<br>
<input class='autoSize type2' value="here too">
Quite simple:
oninput='this.style.width = (this.scrollWidth - N) + "px";'
Where N is some number (2 in the example, 17 on something I'm developing) that is determined experimentally.
Subtracting N prevents this strange extrenuous space from accumulating long before the text reaches the end of the text box.
Compare. Pay careful attention to how the size changes after even just the first character.
<p>Subtracting N:</p>
<input type="text" placeholder="enter lots of text here" oninput='this.style.width = (this.scrollWidth-2) + "px";'>
<p>Not Subtracting N:</p>
<input type="text" placeholder="enter lots of text here" oninput='this.style.width = (this.scrollWidth) + "px";'>
Here is my React solution, it works with any font size, just make sure you have a monospace font (all font character widths are the same on monospace fonts) like i have in my solution, and it will work perfectly.
JS:
const [value, setValue] = useState(0)
HTML:
<input value={value} onChange={(e) => {setValue(e.target.value)}} style={{width: `${value.toString().length}`ch}}/>
CSS:
#import url("https://fonts.googleapis.com/css2?family=B612+Mono&display=swap");
input{
font-family: "B612 Mono", monospace;
}
You can do it even simpler in angularjs using the built-in ng-style directive.
In your html:
<input ng-style="inputStyle(testdata)" ng-model="testdata" />
In your controller:
$scope.testdata = "whatever";
$scope.inputStyle = function(str) {
var charWidth = 7;
return {"width": (str.length +1) * charWidth + "px" };
};
In your css:
input { font-family:monospace; font-size:12px; }
Adjust the charWidth to match the width of your font. It seems to be 7 at a font-size of 12px;
If you use Bootstrap, it could be done very easily:
<div contenteditable="true" class="form-control" style="display: inline"></div>
You will just need to fetch div's content and put it in a hidden input before submitting the form.
Here is my 2 cents.
Create an empty invisible div. Fill it with the input content and return the width to the input field. Match text styles between each box.
$(".answers_number").keyup(function(){
$( "#number_box" ).html( $( this ).val() );
$( this ).animate({
width: $( "#number_box" ).width()+20
}, 300, function() {
});
});
#number_box {
position: absolute;
visibility: hidden;
height: auto;
width: auto;
white-space: nowrap;
padding:0 4px;
/*Your font styles to match input*/
font-family:Arial;
font-size: 30px;
}
.answers_number {
font-size: 30px;
font-family:Arial;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="number" class="answers_number" />
<div id="number_box">
</div>
Here's a simple function to get what is needed:
function resizeInput() {
const input = document.getElementById('myInput');
input.style.width = `${input.scrollWidth}px`;
};
I think you're misinterpreting the min-width CSS property. min-width is generally used to define a minimum DOM width in a fluid layout, like:
input {
width: 30%;
min-width: 200px;
}
That would set the input element to a minimum width of 200 pixels. In this context, "px" stands for "pixels".
Now, if you're trying to check to make sure that input field contains at least one character when a user submits it, you'll need to do some form validation with JavaScript and PHP. If that is indeed what you're attempting to do, I'll edit this answer and do my best to help you out.
I really liked Lyth's answer, but also really wanted it to:
Handle backspace and delete
Not require you to manually add an adjacent tag.
Enforce a min width.
Automatically be applied to elements with a specific class
I adapted his JSFiddle and came up with this. One improvement not present in this fiddle would be to use something like the jQuery CSS Parser to actually read the initial width from the input.textbox-autosize rule, and use that as the minWidth. Right I'm simply using an attribute on the , which makes for a compact demo but is not ideal. as it requires an extra attribute on each input. You might also just want to put the minWidth as 100 right in the JavaScript.
HTML:
<div id='applicationHost'>
<div>Name: <input class='textbox-autosize' data-min-width='100' type="text" /></div>
<div>Email: <input class='textbox-autosize' data-min-width='100' type="email" /></div>
<div>Points: <input class='textbox-autosize' data-min-width='100' type="number" /></div>
</div>
CSS:
#applicationHost {
font-family: courier;
white-space: pre;
}
input.textbox-autosize, span.invisible-autosize-helper {
padding:0;
font-size:12px;
font-family:Sans-serif;
white-space:pre;
}
input.textbox-autosize {
width: 100px; /* Initial width of textboxes */
}
/*
In order for the measurements to work out, your input and the invisible
span need to have the same styling.
*/
JavaScript:
$('#applicationHost').on('keyup', '.textbox-autosize', function(e) {
// Add an arbitary buffer of 15 pixels.
var whitespaceBuffer = 15;
var je = $(this);
var minWidth = parseInt(je.attr('data-min-width'));
var newVal = je.val();
var sizingSpanClass = 'invisible-autosize-helper';
var $span = je.siblings('span.' + sizingSpanClass).first();
// If this element hasn't been created yet, we'll create it now.
if ($span.length === 0) {
$span = $('<span/>', {
'class': sizingSpanClass,
'style': 'display: none;'
});
je.parent().append($span);
}
$span = je.siblings('span').first();
$span.text(newVal) ; // the hidden span takes
// the value of the input
$inputSize = $span.width();
$inputSize += whitespaceBuffer;
if($inputSize > minWidth)
je.css("width", $inputSize) ; // apply width of the span to the input
else
je.css("width", minWidth) ; // Ensure we're at the min width
});
Better is onvalue:
<input id="txt" type="text" onvalue="this.style.width = ((this.value.length + 1) * 8) + 'px';">
It also involves pasting, dragging and dropping, etc.
The best solution is <input ... size={input.value.length} />
Svelte version:
<input type="text" style="width: {tag.length}ch" bind:value={tag} />
I just spend some time figuring out how to do it.
Actually the simplest way I found is to move input value to span just before the input, keeping input 1 symbol width. Though I can't be sure that it fit for your initial need.
Maybe it some extra code, but in react+flux based application it is quite natural solution.
Based off Michael's answer, I have created my own version of this using jQuery. I think it is a cleaner/shorter version of most answers here and it seems to get the job done.
I am doing the same thing as most of the people here by using a span to write the input text into then getting the width. Then I am setting the width when the actions keyup and blur are called.
Here is a working codepen. This codepen shows how this can be used with multiple input fields.
HTML Structure:
<input type="text" class="plain-field" placeholder="Full Name">
<span style="display: none;"></span>
jQuery:
function resizeInputs($text) {
var text = $text.val().replace(/\s+/g, ' '),
placeholder = $text.attr('placeholder'),
span = $text.next('span');
span.text(placeholder);
var width = span.width();
if(text !== '') {
span.text(text);
var width = span.width();
}
$text.css('width', width + 5);
};
The function above gets the inputs value, trims the extra spaces and sets the text into the span to get the width. If there is no text, it instead gets the placeholder and enters that into the span instead. Once it enters the text into the span it then sets the width of the input. The + 5 on the width is because without that the input gets cut off a tiny bit in the Edge Browser.
$('.plain-field').each(function() {
var $text = $(this);
resizeInputs($text);
});
$('.plain-field').on('keyup blur', function() {
var $text = $(this);
resizeInputs($text);
});
$('.plain-field').on('blur', function() {
var $text = $(this).val().replace(/\s+/g, ' ');
$(this).val($text);
});
If this could be improved please let me know as this is the cleanest solution I could come up with.
You would like to change the size attribute as the text changes.
# react
const resizeInput = (e) => {
e.target.setAttribute('size', e.target.value.length || 1);
}
<input
onChange={resizeInput}
size={(propertyInput.current && propertyInput.current.value.length) || 1}
ref={propertyInput}
/>