Offset all artboard size for illustrator CC 2015

offset-artboard-rect.jsx

var offset = 5;//Top,Right,Bottom,Left expand 5px.
var doc = app.activeDocument;
var abs = doc.artboards;

for(var i=0;i<abs.length;i++){

var a = abs[i];
    var rect = a.artboardRect;
    rect[0]=rect[0]-offset;
    rect[1]=rect[1]+offset;                
    rect[2]=rect[2]+offset;
    rect[3]=rect[3]-offset;　                     
    a.artboardRect = rect;
}