document.exists()
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Test if a collection document exists.
Description
The exists() method tests if a collection document exists.
exists() vs. null comparisons
You can use either exists() or a null comparison (== null or != null) to
check the existence or validity of a value. For example:
Product.byId("111").exists() // true
Product.byId("111") != null // trueKey differences:
-
exists()returns an error if called on an unsupported value. -
Null comparisons do not throw errors and work safely on any value.
For example:
// Declare an object. Objects don't support
// an `exists()` method.
let object = { a: "Foo", b: "Bar" }
object.exists() // Returns `invalid_query` error
object != null // Returns true