How to calculate the height of an image with a custom width preserving the aspect ratio with JavaScript

How many times have we dealt with the same issue over and over again? We try to resize an image with a custom width but we need to research how to provide the image with the proper height so it doesn't look funny. For example, if you resize an image with a custom width but you don't care about the new height, you will end up with this (if you set the original height):

Resize Image Without Preserving Aspect Ratio

If you want to keep the aspect ratio of the image, you will need to calculate the new height with the following formula:

(original height / original width) x new width = new height

Which in JavaScript could be implemented like this:

 * Calculates the proper height of an image with a custom width, preserving the original aspect ratio.
 * @param originalHeight 
 * @param originalWidth 
 * @param newWidth 
function determineNewHeight(originalHeight, originalWidth, newWidth){
    return (originalHeight / originalWidth) * newWidth;

In our case, with the example image of 1600px of width and 1200px of height, if I want to resize it to a new image of 800px of width, I would be able to calculate the new height like this:

// This would return: 600
determineNewHeight(1200, 1600, 800);

The result would be 600px so the image can preserve its original aspect ratio and not look funny when resizing it:

Resize Image Preserving Aspect Ratio

Happy coding ❤️!

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