textLength
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since January 2020.
The textLength
attribute, available on SVG <text>
and <tspan>
elements, lets you specify the width of the space into which the text will draw. The user agent will ensure that the text does not extend farther than that distance, using the method or methods specified by the lengthAdjust
attribute. By default, only the spacing between characters is adjusted, but the glyph size can also be adjusted if you change lengthAdjust
.
By using textLength
, you can ensure that your SVG text displays at the same width regardless of conditions including web fonts failing to load (or not having loaded yet).
You can use this attribute with the following SVG elements:
Example
<svg viewBox="0 0 200 60" xmlns="http://www.w3.org/2000/svg">
<text y="20" textLength="6em">Small text length</text>
<text y="40" textLength="120%">Big text length</text>
</svg>
Usage notes
Value |
<length-percentage> |
<number>
|
---|---|
Default value | None |
Animatable | Yes |
<length-percentage>
-
This value specifies the width of the space the text will be adjusted to occupy as absolute length or percentage.
<number>
-
A numeric value outlines a length referring to the units of the current coordinate system.
Interactive example
CSS
.controls {
font:
16px "Open Sans",
"Arial",
sans-serif;
}
SVG
Let's start with the SVG. It's pretty basic, with a 1000-by-300 pixel space mapped into a 10 centimeter by 3 centimeter box.
<svg
width="10cm"
height="3cm"
viewBox="0 0 1000 300"
xmlns="http://www.w3.org/2000/svg">
<rect
x="1"
y="1"
width="998"
height="298"
fill="none"
stroke="green"
stroke-width="2" />
<text
id="hello"
x="10"
y="150"
font-family="sans-serif"
font-size="60"
fill="green">
Hello world!
</text>
</svg>
First, a <rect>
element is used to create and stroke a rectangle to contain the text. Then <text>
is used to create the text element itself, with an id
of "hello"
.
HTML
The HTML is also simple, with only two displayed elements contained inside a grouping <div>
:
<div class="controls">
<input type="range" id="widthSlider" min="80" max="978" />
<span id="widthDisplay"></span>
</div>
The <input>
element, of type "range"
, is used to create the slider control the user will manipulate to change the width of the text. A <span>
element of ID "widthDisplay"
is provided to display the current width value.
JavaScript
Finally, let's have a look at the JavaScript code. It starts by stashing references to the elements it will need to access, using Document.getElementById()
:
const widthSlider = document.getElementById("widthSlider");
const widthDisplay = document.getElementById("widthDisplay");
const textElement = document.getElementById("hello");
const baseLength = Math.floor(textElement.textLength.baseVal.value);
widthSlider.value = baseLength;
widthSlider.addEventListener(
"input",
(event) => {
textElement.textLength.baseVal.newValueSpecifiedUnits(
SVGLength.SVG_LENGTHTYPE_PX,
widthSlider.valueAsNumber,
);
widthDisplay.innerText = widthSlider.value;
},
false,
);
widthSlider.dispatchEvent(new Event("input"));
After fetching the element references, an event listener is established by calling addEventListener()
on the slider control, to receive any input
events which occur. These events will be sent any time the slider's value changes, even if the user hasn't stopped moving it, so we can responsively adjust the text width.
When an "input"
event occurs, we call newValueSpecifiedUnits()
to set the value of textLength
to the slider's new value, using the SVGLength
interface's SVG_LENGTHTYPE_PX
unit type to indicate that the value represents pixels. Note that we have to dive into textLength
to get its baseVal
property; textLength
is stored as an SVGLength
object, so we can't treat it like a plain number.
After updating the text width, the contents of the widthDisplay
box are updated with the new value as well, and we're finished.
Result
Here's what the example looks like. Try dragging the slider around to get a feel for what it does.
Specifications
Specification |
---|
Scalable Vector Graphics (SVG) 2 # TextElementTextLengthAttribute |
Browser compatibility
BCD tables only load in the browser
See also
- SVG Tutorial: Texts
SVGAnimatedLength
andSVGLength
<text>