[devote]

<style>
button {padding: 2px}
</style>
 
<button onclick="
    this.style.height = ( this.getBoundingClientRect().bottom - this.getBoundingClientRect().top ) + 'px';
    alert( 'Высота элемента: ' + (this.getBoundingClientRect().bottom - this.getBoundingClientRect().top))
">click</button>