javascript: 2 assignments in one line of code

this line is taken from the dreamweaver mx generated code when creating a
navigation bar..
2 assigments in one line of code.. does this mean that the variable nbArr is
first allocated new memory and then nbArr is assigned to document.MM_nbOver?
ive never seen 2 assigments in one row before..
document.MM_nbOver = nbArr = new Array();