Collection.count() - zuki/Dexie.js GitHub Wiki

Syntax

collection.count(callback)

Parameters

callback: Function	function (count) { }	optional

Callback Parameters

count: Number	Number of items in the collection

Return Value

Promise

Remarks

If callback is omitted and operation succeeds, returned Promise will resolve with the result of the operation, calling any Promise.then() callback.

If callback is specified and operation succeeds, given callback will be called and the returned Promise will resolve with the return value of given callback.

If operation fails, returned promise will reject, calling any Promise.catch() callback.

Performance Notes

If executed on simple queries, the native IDB count() method will be called (fast execution). If advanced queries are used, the implementation have to execute a query to iterate all items and count them manually.

Examples where count() will be fast

db.[table].count()
db.[table].where(index).equals(value).count()
db.[table].where(index).above(value).count()
db.[table].where(index).below(value).count()
db.[table].where(index).between(a,b).count()
db.[table].where(index).startsWith(value).count()

The reason it is fast in above samples is that they map to basic IDBKeyRange methods only(), lowerbound(), upperbound() and bound().

Examples where count() will have to count manually:

db.[table].where(index).equalsIgnoreCase(value).count()
db.[table].where(index).startsWithIgnoreCase(value).count()
db.[table].where(index).anyOf(valueArray).count()
db.[table].where(index).above(value).and(filterFunction).count()
db.[table].where(index1).above(value1).or(index2).below(value2).count()