你可以将 clientWidth、clientHeight、offsetWidth 和 offsetHeight 绑定添加到任何元素，Svelte 将使用 ResizeObserver 更新绑定值：
¥You can add clientWidth, clientHeight, offsetWidth and offsetHeight bindings to any element, and Svelte will update the bound values using a ResizeObserver:
App
<div bind:clientWidth={w} bind:clientHeight={h}>
<span style="font-size: {size}px" contenteditable>{text}</span>
<span class="size">{w} x {h}px</span>
</div>这些绑定是只读的 - 更改 w 和 h 的值不会对元素产生任何影响。
¥These bindings are readonly — changing the values of w and h won’t have any effect on the element.
display: inline元素没有宽度或高度（具有 ‘intrinsic’ 尺寸的元素除外，例如<img>和<canvas>），并且无法通过ResizeObserver进行观察。你需要将这些元素的display样式更改为其他样式，例如inline-block。
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<script>
let w = $state();
let h = $state();
let size = $state(42);
</script>
<label>
<input type="range" bind:value={size} min="10" max="100" /> font size ({size}px)</label>
<div>
<span style="font-size: {size}px" contenteditable>edit this text
</span>
<span class="size">{w} x {h}px</span></div>
<style>
div {position: relative;
display: inline-block;
padding: 0.5rem;
background: hsla(15, 100%, 50%, 0.1);
border: 1px solid hsl(15, 100%, 50%);
}
.size {position: absolute;
right: -1px;
bottom: -1.4em;
line-height: 1;
background: hsl(15, 100%, 50%);
color: white;
padding: 0.2em 0.5em;
white-space: pre;
}
</style>