This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2020.
Note: This feature is available in Web Workers.
The read-only actualBoundingBoxAscent property of the TextMetrics interface is a double giving the distance from the horizontal line indicated by the CanvasRenderingContext2D.textBaseline attribute to the top of the bounding rectangle used to render the text, in CSS pixels.
const canvas = document.createElement("canvas");
const ctx = canvas.getContext("2d");
const text = ctx.measureText("foo"); // returns TextMetrics object
text.actualBoundingBoxAscent; // 8;
| Specification |
|---|
| HTML> # dom-textmetrics-actualboundingboxascent-dev> |
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Opera | Safari | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | WebView Android | WebView on iOS | |
actualBoundingBoxAscent |
77 | 79 | 74 | 64 | 11.1 | 77 | 79 | 55 | 11.3 | 12.0 | 77 | 11.3 |
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https://developer.mozilla.org/en-US/docs/Web/API/TextMetrics/actualBoundingBoxAscent