js/libs/ember-1.5.1.js
function(keyName, decrement) {
    if (Ember.isNone(decrement)) { decrement = 1; }
    Ember.assert("Must pass a numeric value to decrementProperty", (!isNaN(parseFloat(decrement)) && isFinite(decrement)));
    set(this, keyName, (get(this, keyName) || 0) - decrement);
    return get(this, keyName);
  }
function(keyName, decrement) {
    if (Ember.isNone(decrement)) { decrement = 1; }
    Ember.assert("Must pass a numeric value to decrementProperty", (!isNaN(parseFloat(decrement)) && isFinite(decrement)));
    set(this, keyName, (get(this, keyName) || 0) - decrement);
    return get(this, keyName);
  }
Set the value of a property to the current value minus some amount.

```javascript
player.decrementProperty('lives');
orc.decrementProperty('health', 5);
```

@method decrementProperty
@param {String} keyName The name of the property to decrement
@param {Number} decrement The amount to decrement by. Defaults to 1
@return {Number} The new property value