This is a pretty compact approach...

```javascript
(_propertyValue = Math.round ((_properties.opacity + '' || '#') * 100) < 100
```

If the value is an empty string, it will be turned into #, which will produce NaN when multiplied by 100, and NaN is not less than 100. For  the number 0, the string '0' will be retained and coerced back to 0 when multiplied. This is more compact and does not involve an additional function call, which is more important for animations for opacity where it is called repeatedly.