var elemento = document.getElementById("a"),

    height = getComputedStyle(elemento).height,

    width = getComputedStyle(elemento).width,

    display = getComputedStyle(elemento).display,

    salida1 = document.getElementById("b"),

    salida2 = document.getElementById("c"),

    salida3 = document.getElementById("d");

salida1.innerHTML = "Height: " + height;

salida2.innerHTML = "Width: " + width;

salida3.innerHTML = "Display: " + display;