Document Object Model

> Нужно вставить узел перед. Как это сделать?

oElement = object.insertAdjacentElement(sWhere, oElement)

sWhere Required.
String that specifies where to insert the HTML element, using one of the following values: beforeBegin Inserts oElement immediately before the object.
afterBegin Inserts oElement after the start of the object but before all other content in the object.
beforeEnd Inserts oElement immediately before the end of the object but after all other content in the object.
afterEnd Inserts oElement immediately after the end of the object.

oElement Required.
Object that specifies the element to be inserted adjacent to the object that invoked the insertAdjacentElement method.

То есть:
[beforeBegin]<oElement>[afterBegin] oElement content [beforeEnd]</oElement>[afterEnd]