Evaluate expression from within a script

I got the camera position in script via 

app.project.activeItem.activeCamera.transform.position;

Is there a way to convert the position object to a string so it can be used for further processing and passed around ?

For example, I tried

app.project.activeItem.activeCamera.transform.position.toString() ;

- I got 

[object Property]

Typically you'd add the expression to a suitable property.expression, then read the value of that property.

For example, you have an A & B layer, also a Text layer with the Source Text property selected:

myProperty = app.project.activeItem.selectedProperties[0];
myProperty.expression = 'length(thisComp.layer("A").position, thisComp.layer("B").position);';
lengthResult = myProperty.value;
$.writeln(lengthResult.toString());

If you want more than just a static value then you'll need to loop through sampling each frame with valueAtTime().

I think it's only with certain expressions that took time to evaluate that you need to do things like Convert To Keyframes, but even that was supposedly addressed in CC 2014.

Also a quick google for "distance between 2 points javascript" will give you numerous examples you could just use directly in your script if you want to bypass the expressions.

var Apos = [3300,1124];
var Bpos = [1064,1208];
var result = 0;
for (var x=0; x< Apos.length; x++) {
	result += Math.pow(Bpos[x]-Apos[x], 2);
}
result = Math.sqrt(result);
$.writeln("length = " + result);

You can't on the plain expression, but you can of course convert everything to keyframes by invoking the respective menu command. That's a trick that in the past has been employed by several scripts - apply an expression, convert to keyframes, retrieve the keyframe values, delete keyframes if needed. The only caveat here is that eventually things may get too slow and the script may break or AE crashes attempting to actually draw the keyframes on teh timeline.

Mylenium