Several operators can be applied to objects of any type.
Engine Compatibility
In the node pico engine, the target types for the as()
function and the results returned from the typeof()
function are these values:
"Array"
"Boolean"
"Map"
"Null"
"Number"
"RegExp"
"String"
The following coercions are valid:
- Strings can be coerced to numbers and regular expressions.
- Numbers can be coerced to strings.
- Regular expressions can be coerced to strings.
- Any expression can be coerced to Boolean.
An error is thrown for other attempted coercions, unless the value being coerced by as()
is already of the target type.
as()
The as()
operators coerces objects of one type to be an object of another. The target type is given as a string argument to the operator. The following types are available in KRL:
str
. Coerce the target to have type stringnum
. Coerce the target to have type numberregexp
. Coerce the target to have type regular expressiontrail
. Coerce the target to have type trail
For example, the following constructs a string and then turns it into a regular expression that can be used by the replace() operator:
("re/q=" + q + "/i").as("regexp")
Not every type can be coerced to another. The following coercions are valid:
- Strings can be coerced to numbers and regular expressions.
- Numbers can be coerced to strings.
- Regular expressions can be coerced to strings.
- Trails can be coerced to arrays.
isnull()
The isnull()
operator returns true of the object is null (undefined) and false otherwise.
doesnotexist.isnull(); // returns true
klog()
The klog()
operator writes an optional message, given as a string argument, and the value of the object to the debug log.
x = some_arr.filter(function(x){x == 5}).klog("Value after filter: ").head();
typeof()
The typeof()
operator returns the type of the object to which it is applied. For example:
nums = [1, 2, 3] nums_type = nums.typeof() // nums_type = "array"
Valid values include
- num
- str
- array
- hash (for maps)