button.setAttribute('style', 'float: right;');

button.style = 'float: right;';

button.style.setAttribute('cssFloat','right');

button.style.cssFloat = 'right';

function setStyle(el,spec) {
    for (var n in spec) {
        el.style[n] = spec[n];
    }
}

setStyle(button,{
    cssFloat : 'right',
    border : '2px solid black'
});

button.style.cssText = 'float: right;';

button.style.cssFloat = 'right';

button.className = 'a class that matches a pre-written CSS rule-set';

//Set Property

this.setProperty = function (a, b) {
var c = this.element.getAttribute("style");
var d;
if (!c) {
    this.element.setAttribute("style", a + ":" + b);
return;
} else {
    d = c.split(";")
}

for (var e = 0; e < d.length; e++) {
    var f = d[e].split(":");
    if (f[0].toLowerCase().replace(/^s+|s+$/g, "").indexOf(a.toLowerCase().replace(/^s+|s+$/g, "")) == 0) {
       d[e] = a + ":" + b
    }
}

d[d.length] = a + ":" + b;
this.element.setAttribute("style", d.join(";"))
}

//Remove Property
this.removeProperty = function (a) {
var b = this.element.getAttribute("style");
var c;
if (!b) {
    return
} else {
    c = b.split(";")
}

for (var d = 0; d < c.length; d++) {
    var e = c[d].split(":");
    if (e[0].toLowerCase().replace(/^s+|s+$/g, "").indexOf(a.toLowerCase().replace(/^s+|s+$/g, "")) == 0) {
        c[d] = ""
    }
}

this.element.removeAttribute("style");
this.element.setAttribute("style", c.join(";").replace(";;", ";"))
}

node.style.z-index = 50;/Firefox says error, invalid assignment left hand side.

node.style["z-index"] = "50";//Works without error