method isEqual

This method returns true if the arithmetic value of the bigInt equals the argument.

var maxSize = shell.serviceManager.basics.bigInt;
maxSize.value = 1024 * 1024 * 1024;         // maxSize = 1 GB
maxSize.multiply(10);                       // maxSize = 10 GB
if (maxSize.isEqual(fileStream.size))
{
    // File size just right - do something here
}