[Dan Ebberts]

Here’s a simple example. Try adding a checkbox to your text layer and add this expression to the Source Text property (edit the font names to ones that make sense on your system):

cb = effect("Checkbox Control")("Checkbox").value;
cb ? style.setFont("ArialMT") : style.setFont("LucidaConsole");

[Dan Ebberts]

Try this simple setup. Make your text layers the first 5 layers in your comp’s layer stack. Add a null named “control” below the text layers. Add a slider named “gap” to the control layer and set it to the horizontal distance you want between text layers. Add this expression to each text layer’s Position property:

if (index > 1){
  gap = thisComp.layer("control").effect("gap")("Slider");
  L = thisComp.layer(index-1);
  r = L.sourceRectAtTime(0);
  p = L.toComp([r.left + r.width, r.top]);
  x = p[0] + gap;
  [x,value[1]]
}else
  value

[Dan Ebberts]

Is this for an expression selector? If so, try this:

p = text.sourceText;
t = 0;
if (p.numKeys > 0){
	n = p.nearestKey(time).index;
	if (time < p.nearestKey(time).time && (n > 1)) n--;
	t = p.key(n).time;
}
wiggle(effect("wiggles / sec")("Slider"),effect("wiggle amount")("Slider"),1.0,0.5,t)

[Dan Ebberts]

Try replacing your posterizeTime() statement with this:

seed = 1;
if (numKeys > 0){
	seed = nearestKey(time).index;
	if (time < nearestKey(time).time) seed--;
}
seedRandom(seed,true);

and if you’re using the Expression Selector expression, try replacing the seedRandom() statement with this:

seed = 1;
p = text.sourceText;
if (p.numKeys > 0){
	seed = p.nearestKey(time).index;
	if (time < p.nearestKey(time).time) seed--;
}
seedRandom(textIndex*1000 + seed,true);

[Dan Ebberts]

You may have figured it out already, but to make the expression selectors sync up to the randomization of your posterizeTime(), you could replace the seedRandom() statement with something like this:

seedRandom(textIndex*1000 + Math.floor(time/2),true);

[Dan Ebberts]

Just add this to the end of the style .set commands:

.setAllCaps(Math.round(random()), i, 1)

[Dan Ebberts]

For random upper/lower case, you could use a Source Text expression like this:

txt = "";
seedRandom(index,true);
for (i = 0; i < value.length; i++){
  txt += random(1) < .5 ? value[i].toUpperCase() : value[i].toLowerCase();
}
txt

For other properties, like rotation, you can add a Rotation Animator (and set the Rotation value to say 25 degrees), add an Expression Selector, and delete the Range Selector. Then add this expression to Expression Selector’s Amount property:

seedRandom(textIndex,true);
random(-100,100)

[Dan Ebberts]

My guess, based on the error message, is that you have the expression engine set to Legacy Extendscript. Try:

File > Project Settings > Expressions > JavaScript

[Dan Ebberts]

Can you post the whole expression (or a link to where you got it)?

[Dan Ebberts]

Yeah, I sniffed around for a while using propterGroup() but I didn’t get anywhere. I don’t think it’s there, but I’d be happy to be proven wrong.