in JSDOMParser.js [879:898]
setStyle(styleName, styleValue) {
var value = this.node.getAttribute("style") || "";
var index = 0;
do {
var next = value.indexOf(";", index) + 1;
var length = next - index - 1;
var style =
length > 0 ? value.substr(index, length) : value.substr(index);
if (style.substr(0, style.indexOf(":")).trim() === styleName) {
value =
value.substr(0, index).trim() +
(next ? " " + value.substr(next).trim() : "");
break;
}
index = next;
} while (index);
value += " " + styleName + ": " + styleValue + ";";
this.node.setAttribute("style", value.trim());
},