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Set width in HTML In HTML, you can use the width attribute to set the width of an element. Alternatively, you can also use the size attribute to define the width of the <input> .
The size attribute specifies the visible width, in characters, of an <input> element. Note: The size attribute works with the following input types: text, search, tel, url, email, and password. Tip: To specify the maximum number of characters allowed in the <input> element, use the maxlength attribute.
Definition and UsageThe width attribute specifies the width of the <input> element. Note: The width attribute is used only with <input type="image"> . Tip: Always specify both the height and width attributes for images. If height and width are set, the space required for the image is reserved when the page is loaded.
The width will be the value of the size attribute in characters that the input will display. Value should be an integer greater than zero. When not defined, the width of most input elements defaults to 20.
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:
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; }<input>That example would resize "elem" 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.
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