How to 'unwatch' an expression

Question

Say I have an ng-repeat with a big array.

When ng-repeat runs, it adds every element of that array to an isolated scope, as well as having the array itself in a scop

Answer 1

$watch returns a function that unbinds the $watch when called. So this is all you need for "watchOnce":

var unwatchValue = scope.$watch('value', function(newValue, oldValue) {
  // Do your thing
  unwatchValue();
});