Adobe Photoshop. ESTK. Copy text to system clipboard.

Hello, everybody!

My task is: a script, that copies the dimensions of an image (or other predefined text) to the system clipboard:

#target Photoshop

var w = Math.round(activeDocument.width);
var h = Math.round(activeDocument.height);
var str = "image size is : " + w + " X " + h;

My question is: How to copy "str" to system clipboard?