layout	api-command
language	JavaScript
permalink	api/javascript/count/
command	count
io	sequence number binary number
related_commands	map reduce sum avg min max group map/ reduce/ sum/ avg/ min/ max/ group/

Command syntax

{% apibody %} sequence.count([value | predicate_function]) → number binary.count() → number string.count() → number object.count() → number array.count() → number r.count(sequence | binary | string | object[, predicate_function]) → number {% endapibody %}

Description

Counts the number of elements in a sequence or key/value pairs in an object, or returns the size of a string or binary object.

When count is called on a sequence with a predicate value or function, it returns the number of elements in the sequence equal to that value or where the function returns true. On a binary object, count returns the size of the object in bytes; on strings, count returns the string's length. This is determined by counting the number of Unicode codepoints in the string, counting combining codepoints separately.

Example: Count the number of users.

r.table('users').count().run(conn, callback);

Example: Count the number of 18 year old users.

r.table('users')('age').count(18).run(conn, callback);

Example: Count the number of users over 18.

r.table('users')('age').count(function(age) { 
    return age.gt(18)
}).run(conn, callback);

r.table('users').count(function(user) {
    return user('age').gt(18)
}).run(conn, callback)

Example: Return the length of a Unicode string.

r.expr("こんにちは").count().run(conn, callback);
// Result passed to callback
5

Example: Return the length of an array.

r.expr(['0','1','2']).count().run(conn, callback);
// Result passed to callback
3