Return the format of an image.

getImageFormat.js

/**
 * Return the natural dimensions of an image.
 * @string img - The image to get the dimensions of.
 * @return {object} - The natural width of the image.
 * @return {null} - If the image has no natural dimensions.
 */

 function getNaturalDimensions({ naturalWidth, naturalHeight }) {
    // get the image format from the src attribute.
    let width = naturalWidth;
    let height = naturalHeight;

    if (width && height) {
        // return the natural width and height of the image.
        return { width, height };
    } else {
        // return null if the image has no natural dimensions.
        return { width: null, height: null };
    }
}

/**
 * Return the format of an image.
 * @string img - The image to get the format of.
 * @return {string} - The format of the image.
 * @return {null} - If the image has no format.
 */

function getImageFormat(img) {
    // get the image format from the src attribute.
    const { width, height } = getNaturalDimensions(img);

    if (width && height) {
        if (width > height) {
            // return landscape if the width is greater than the height.
            return 'landscape';
        } else if (width < height) {
            // return portrait if width is less than height
            return 'portrait';
        } else if (width === height) {
            // return square if width and height are equal
            return 'square';
        } else {
            // return null if the image has no format.
            return null;
        }
    }

    return null;
}