Select a set of or single entities by components or an entity's ID.
Crafty uses syntax similar to jQuery by having a selector engine to select entities by their components.
If there is more than one match, the return value is an Array-like object listing the ID numbers of each matching entity. If there is exactly one match, the entity itself is returned. If you're not sure how many matches to expect, check the number of matches via Crafty(...).length. Alternatively, use Crafty(...).each(...), which works in all cases.
Crafty("MyComponent")
Crafty("Hello 2D Component")
Crafty("Hello, 2D, Component")
The first selector will return all entities that have the component MyComponent. The second will return all entities that have Hello and 2D and Component whereas the last will return all entities that have at least one of those components (or).
Crafty("*")
Passing * will select all entities.
Crafty(1)
Passing an integer will select the entity with that ID.
Finding out the ID of an entity can be done by returning the property 0.
var ent = Crafty.e("2D");
ent[0]; //ID