Operators

Operator expressions are similar to functions that take arguments.

abs	$abs	Returns the absolute value of a number
acos	$acos	Returns a numeric value between 0 and π radians for x between -1 and 1
acosh	$acosh	Returns the inverse hyperbolic cosine of a number
acl	$acl	Not applicable
add	$add	Adds two or more array properties or expressions. In addition to numbers, a single Date value may be included in the array.
and	$and	Evaluates to true if all conditions in the passed in array evaluate to true
asin	$asin	Returns the arcsine (in radians) of a number
asinh	$asinh	Returns the hyperbolic arcsine of a number
atan	$atan	Returns the arctangent (in radians) of a number
atan2	$atan2	Returns the angle in the plane (in radians) between the positive x-axis and the ray from (0,0) to the point (x,y)
atanh	$atanh	Returns the hyperbolic arctangent of a number
ceil	$ceil	Always rounds a number up to the next largest integer
convert	$convert	Not applicable
cos	$cos	Returns the cosine of the specified angle, which must be specified in radians
dateFromParts	$dateFromParts	Returns a date from the specified parts (year, month, and day values)
dateFromString	$dateFromString	Converts a date object to a string in a specified format, and expects an array of [date_expression]
dateToParts	$dateToParts	Returns a document that contains the constituent parts of a given Date value as individual properties
dateToString	$dateToString	Converts a date object to a string according to a user-specified format
dayOfMonth	$dayOfMonth	Returns the day of the month for a date as a number between 1 and 31
dayOfWeek	$dayOfWeek	Returns the day of the week for a date as a number between 1 (Sunday) and 7 (Saturday)
dayofYear	$dayofYear	Returns the day of the year for a date as a number between 1 and 366
degreestoRadians	$degreestoRadians	Converts an input value measured in degrees to radians
divide	$divide	Divides one number by another and returns the result
exp	$exp	Takes the e^n of a number
floor	$floor	Returns the largest integer less than or equal to the specified number
hour	$hour	Returns the hour portion of a date as a number between 0 and 23
isoDayOfWeek	$isoDayOfWeek	Returns the weekday number in ISO 8601 format, ranging from 1 (Monday) to 7 (Sunday)
isoWeek	$isoWeek	Returns the week number in ISO 8601 format, ranging from 1 to 53
isoWeekYear	$isoWeekYear	Returns the year number in ISO 8601 format
log	$log	Takes the log of the first number in the second number's base
log10	$log10	Calculates the log base 10 of a number and returns the result as a double
let	$let	Binds variables for use in the specified expression, and returns the result of the expression View let for more information on how the let variable is used in mongodb operations.
ltrim	$ltrim	Removes whitespace characters, including null, or the specified characters from the beginning of a string
mergeObjects	$mergeObjects	Combines multiple documents into a single document
milliseconds	$milliseconds	Returns the millisecond portion of a date as an integer between 0 and 999
minute	$minute	Returns the minute portion of a date as a number between 0 and 59
moment	$moment	Used as a wrapper for the moment.js library to parse, validate, manipulate, and display dates and times in JavaScript Example to determine the difference between two dates: $moment: [date, { 'diff': [date2, 'days'] }]
month	$month	Returns the month of a date as a number between 1 and 12
multiply	$multiply	Multiplies the value of a field by a number
omit	$omit	Not applicable
or	$or	Performs a logical OR operation on an array of two or more and selects the documents that satisfy at least one of the arguments
pathTo	$pathTo	Sets a path and creates deep objects Example: $pathTo: [{ $literal: {} }, 'configuration.reporting.enabled', true]
pick	$pick	Not applicable
radiansToDegrees	$radiansToDegrees	Converts an input value measured in radians to degrees
regexFind	$regexFind	Provides regular expression (regex) pattern matching capability in aggregation expressions
regexFindAll	$regexFindAll	Provides regex pattern matching capability in aggregation expressions. The operator returns an array of documents that contains information on each match.
regexMatch	$regexMatch	Performs regex pattern matching and returns
replaceAll	$replaceAll	Replaces all instances of a search string in an input string with a replacement string
replaceOne	$replaceOne	Replaces the first instance of a search string in an input string with a replacement string
rtrim	$rtrim	Removes whitespace characters, including null, or the specified characters from the end of a string
second	$second	Returns the second portion of a date as a number between 0 and 59, but can be 60 to account for leap seconds
sin	$sin	Returns the sine of a value that is measured in radians
split	$split	Divides a string into an array of substrings based on a delimiter
sqrt	$sqrt	Calculates the square root of a positive number and returns the result as a double
stdDevPop	$stdDevPop	Calculates the population standard deviation of the input values
stdDevSamp	$stdDevSamp	Calculates the sample standard deviation of the input values
strcasecmp	$strcasecmp	Performs a case-insensitive comparison of two strings
strLenBytes	$strLenBytes	Returns the number of UTF-8 encoded bytes in the specified string
strLenCP	$strLenCP	Returns the number of UTF-8 code points in the specified string
substr	$substr	Returns the number of UTF-8 encoded bytes in the specified string
substrBytes	$substrBytes	Returns the substring of a string
substrCP	$substrCP	Returns the substring of a string
tan	$tan	Returns the tangent of a value that is measured in radians
toDate	$toDate	Converts a value to date
toLower	$toLower	Converts a string to lowercase, returning the result
toUpper	$toUpper	Converts a string to uppercase, returning the result
trim	$trim	Removes whitespace characters, including null, or the specified characters from the beginning and end of a string
week	$week	Returns the week of the year for a date as a number between 0 and 53
year	$year	Returns the year portion of a date