for of loop that stops at last object of array
It hit me,

function returnSuggestedColleaguesWithExpertiseHeight(): number {
    let height = element[0].clientHeight;
    const childElements = &lt;[HTMLElement]&gt;element[0].children;
    for (let i = 0; i &lt; childElements.length - 1; i++) {
        height -= Math.ceil(childElements[i].clientHeight);
    }
    return height;
}