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This function allows you to programmatically lighten or darken a hex color by a specific amount. Simply pass in a string like "3F6D2A" for the color and an integer amt for the amount to lighten or darken. To darken, pass in a negative number (e.g., -20).
<code class="js">function LightenDarkenColor(col, amt) { col = parseInt(col, 16); return (((col & 0x0000FF) + amt) | ((((col >> 8) & 0x00FF) + amt) << 8) | (((col >> 16) + amt) << 16)).toString(16); } // TEST console.log(LightenDarkenColor("3F6D2A", 40));
Faster and smaller version:
<code class="js">function LightenDarkenColor(col, amt) { var num = parseInt(col, 16); var r = (num >> 16) + amt; var b = ((num >> 8) & 0x00FF) + amt; var g = (num & 0x0000FF) + amt; var newColor = g | (b << 8) | (r << 16); return newColor.toString(16); } // TEST console.log(LightenDarkenColor("3F6D2A", -40));
Handle colors with or without the # prefix:
<code class="js">function LightenDarkenColor(col, amt) { var usePound = false; if ( col[0] == "#" ) { col = col.slice(1); usePound = true; } var num = parseInt(col, 16); var r = (num >> 16) + amt; if ( r > 255 ) r = 255; else if (r < 0) r = 0; var b = ((num >> 8) & 0x00FF) + amt; if ( b > 255 ) b = 255; else if (b < 0) b = 0; var g = (num & 0x0000FF) + amt; if ( g > 255 ) g = 255; else if ( g < 0 ) g = 0; return (usePound?"#":"") + (g | (b << 8) | (r << 16)).toString(16); }</code>
To use the function, simply pass in the hex color string you want to lighten or darken, and the amount you want to adjust it by. For example, the following code lightens the color "3F6D2A" by 40:
<code class="js">const lightenedColor = LightenDarkenColor("3F6D2A", 40); console.log(`Lightened Color: ${lightenedColor}`); // Output: 7FADEE</code>
The performance of this function is optimized for speed and size. It uses bitwise operations to manipulate the color values, which makes it extremely fast. The function is also very small, making it ideal for use in small applications.
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