Resize the width of a text box to fit its content automatically
Written byPhuoc Nguyen
Created
29 Feb, 2020
Category
Level 2 — Intermediate
Let's say that an input has the
`id`
of `textbox`
as below:html
<input type="text" id="textbox" />
To adjust its width based on its content dynamically, we create a fake element whose content is the same as the input value. And we set the input's width as the fake element's width.
js
// Create a div element
const fakeEle = document.createElement('div');
// Hide it completely
fakeEle.style.position = 'absolute';
fakeEle.style.top = '0';
fakeEle.style.left = '-9999px';
fakeEle.style.overflow = 'hidden';
fakeEle.style.visibility = 'hidden';
fakeEle.style.whiteSpace = 'nowrap';
fakeEle.style.height = '0';
// We copy some styles from the textbox that effect the width
const textboxEle = document.getElementById('textbox');
// Get the styles
const styles = window.getComputedStyle(textboxEle);
// Copy font styles from the textbox
fakeEle.style.fontFamily = styles.fontFamily;
fakeEle.style.fontSize = styles.fontSize;
fakeEle.style.fontStyle = styles.fontStyle;
fakeEle.style.fontWeight = styles.fontWeight;
fakeEle.style.letterSpacing = styles.letterSpacing;
fakeEle.style.textTransform = styles.textTransform;
fakeEle.style.borderLeftWidth = styles.borderLeftWidth;
fakeEle.style.borderRightWidth = styles.borderRightWidth;
fakeEle.style.paddingLeft = styles.paddingLeft;
fakeEle.style.paddingRight = styles.paddingRight;
// Append the fake element to `body`
document.body.appendChild(fakeEle);
The function below sets the HTML for the fake element, calculates its width and sets the result to the original input.
js
const setWidth = function () {
const string = textboxEle.value || textboxEle.getAttribute('placeholder') || '';
fakeEle.innerHTML = string.replace(/\s/g, '&' + 'nbsp;');
const fakeEleStyles = window.getComputedStyle(fakeEle);
textboxEle.style.width = fakeEleStyles.width;
};
This post introduces more ways to measure the width of given text in given font
Finally, we invoke the
`setWidth`
function when users change the input value by listening on the `input`
event:js
setWidth();
textboxEle.addEventListener('input', function (e) {
setWidth();
});
#Demo
#See also
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Phước Nguyễn