30 lines
951 B
Markdown
30 lines
951 B
Markdown
---
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title: changeLightness
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tags: string,browser,regexp,intermediate
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---
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Changes the lightness value of an `hsl()` color string.
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- Use `String.prototype.match()` to get an array of 3 strings with the numeric values.
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- Use `Array.prototype.map()` in combination with `Number` to convert them into an array of numeric values.
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- Make sure the lightness is within the valid range (between `0` and `100`), using `Math.max()` and `Math.min()`.
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- Use a template literal to create a new `hsl()` string with the updated value.
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```js
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const changeLightness = (delta, hslStr) => {
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const [hue, saturation, lightness] = hslStr.match(/\d+/g).map(Number);
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const newLightness = Math.max(
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0,
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Math.min(100, lightness + parseFloat(delta))
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);
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return `hsl(${hue}, ${saturation}%, ${newLightness}%)`;
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};
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```
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```js
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changeLightness(10, 'hsl(330, 50%, 50%)'); // 'hsl(330, 50%, 60%)'
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changeLightness(-10, 'hsl(330, 50%, 50%)'); // 'hsl(330, 50%, 40%)'
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```
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