In MongoDB, you can use the $subtract aggregation pipeline operator to subtract numbers and/or dates.
In MongoDB, the $add aggregation pipeline operator adds values together. Such values can be numbers, or they can be numbers and a date.
The $add operator accepts the values as arguments. The arguments can be any valid expression as long as they resolve to either all numbers or to numbers and a date.
In MongoDB, the $anyElementTrue aggregation pipeline operator evaluates an array as a set and returns true if any of the elements are true.
If none of the elements is true, then it returns false.
An array’s element is true if it’s not false, null, 0, or undefined.
In MongoDB, the $allElementsTrue aggregation pipeline operator evaluates an array as a set and returns true if no element in the array is false.
If the array contains an element that is false, then $allElementsTrue returns false.
An array’s element is true if it’s not false, null, 0, or undefined.
In MongoDB, the $toUpper aggregation pipeline operator converts a string to uppercase and returns the result.
In MongoDB, the $toLower aggregation pipeline operator converts a string to lowercase and returns the result.
In MongoDB, you can use the $exists element query operator to match documents that contain a specific field.
You can also use it to match documents that don’t contain a specific field.
You can also use it in conjunction with other operators such $nin to match documents where a given field exists, but it doesn’t contain a specific value.
In MongoDB, the cursor.forEach() method iterates the cursor to apply a JavaScript function to each document from the cursor.