Array

Array

Arrays can be declared as constants in a flowgraph or variables in user defined functions. To create an array from your data in a Juttle pipeline, use the pluck reducer.

The Array module exposes a limited set of operations on array variables.

Array.concat

Combine the elements of a list of arrays into a single array

Array.concat(array1, array2, ...)

Parameter	Description	Required?
`array1`	The first elements in the resulting array	Yes
`array2`	Elements to append to array1	No
`...`	Any number of additional arrays	No

Example: Concatenate ["hello"], [] and ["world"] into ["hello", "world"]

emit -points [{hello: ['hello'], world: ['world']}]
| put message = Array.concat(hello, [], world)
| keep message

Array.indexOf

Search an array and return the zero-based index of the first match, or -1 if there is no match.

Array.indexOf(array, searchvalue)

Parameter	Description	Required?
`array`	The array to search	Yes
`searchvalue`	The value for which to search	Yes

Example: Search for a random integer in an array of random integers

emit -limit 10 -every :.1 second:
| put values=(Math.round(Math.random()*10))
| reduce pluck(values)
| put searchvalue=(Math.round(Math.random()*10))
| put index=Array.indexOf(pluck, searchvalue)

Array.join

Combine the elements of an array into a string

Array.join(array, separator)

Parameter	Description	Required?
`array`	Array whose elements to join	Yes
`separator` Separator to delimit the joined elements	No; defaults to `','`

Example: Join ['joe','meg','bob','may'] into the string 'joe,meg,bob,may'

emit -points [{people: Array.join(['joe','meg','bob','may'], ',')}]

Array.lastIndexOf

Search an array and return the zero-based index of the last match, or -1 if there is no match.

Array.lastIndexOf(array, searchvalue)

Parameter	Description	Required?
`array`	The array to search	Yes
`searchvalue`	The value for which to search	Yes

Example: Search for a random integer in an array of random integers

emit -points [{result: Array.lastIndexOf(['A','B', 'B'], 'B')}]

Array.length

Return the number of items in an array.

Array.length(array)

Parameter	Description	Required?
`array`	The array to measure	Yes

Example: Create an array containing a random number of values, then count them

const random_length=(Math.round(Math.random()*10));
;
emit -limit random_length -every :.1 second:
| put values=(Math.round(Math.random()*10))
| reduce pluck(values)
| put length=Array.length(pluck)

Array.pop

Remove the last element of an array and return it

Array.pop(array)

Parameter	Description	Required?
`array`	Array to pop an element from	Yes

Example: Pop the element 'b' off ['a', 'b']

emit -points [{array: ['a','b']}]
| put result = Array.pop(array)

Array.push

Add an element to the end of an array

Array.push(array, element)

Parameter	Description	Required?
`array`	Array to add `element`to	Yes
`element`	Element to add	Yes

Example: Push 'pajama' and 'potatoes' into the array ['banana']

emit -points [{array: ["banana"]}]
| put elements = Array.push(array, 'pajama', 'potatoes')

Array.reverse

Reverse the order of elements in an array

Array.reverse(array)

Parameter	Description	Required?
`array`	Array reverse	Yes

Example: Reverse ['a', 'b'], yielding ['b', 'a']

emit -points [{array: ['a','b']}]
| put result = Array.reverse(array)

Array.shift

Removes and returns the first element of an array

Array.shift(array)

Parameter	Description	Required?
`array`	Array to take first element from	Yes

Example: Take the element 'a' out of ['a', 'b']

emit -points [{array: ['a','b']}] 
| put result = Array.shift(array)

Array.slice

Returns a subarray of the given array

Array.slice(array, start, end)

Parameter	Description	Required?
`array`	Array to return a slice of	Yes
`start`	Index of subarray start	No; defaults to 0
`end`	Index of subarray end	No; defaults to end of array

Example: Take the slice ['banana'] of the array ['banana', 'pajama']

emit -points [{array: ["banana", "pajama"]}]
| put elements = Array.slice(array, 0, 1)
| keep elements, array

Array.sort

Sort an array. If the array contains numbers, they are sorted in increasing order. If it contains strings, they are sorted alphabetically. Sorting a mixed array is an error.

Array.sort(array)

Parameter	Description	Required?
`array`	Array to sort	Yes

Example: Sort ['c', 'a', 'b'], yielding ['a', 'b', 'c'].

emit -points [{array: ['c', 'a','b']}]
| put result = Array.sort(array)

Array.splice

Removes and returns a subarray, and replaces the subarray with given elements in the input array

Array.splice(array, start, end, elements...)

Parameter	Description	Required?
`array`	Array to splice	Yes
`start`	Start of subarray to replace	No; defaults to 0
`end`	End of subarray	No; defaults to end of `array`
`elements`	List of elements to add	No; defaults to none

Example: Replace 'banana' with 'potatoes' and return ['banana'] given the array ['banana', 'pajama'].

emit -points [{array: ["banana", "pajama"]}]
| put elements = Array.splice(array, 0, 1, 'potatoes')

Array.toString

Returns a string representation of a given array.

Array.toString(array)

Parameter	Description	Required?
`array`	The array to stringify	Yes

Example: Stringify ["hello", "goodbye"], yielding the string ["hello", "goodbye"].

emit -points [{result: Array.toString(["hello", "goodbye"])}]

Array.unshift

Add an element to the beginning of an array

Array.unshift(array, element)

Parameter	Description	Required?
`array`	Array to add element to	Yes
`element`	Element to add	Yes

Example: Add 'pajama' and 'potatoes' to the beginning of ['banana']

emit -points [{array: ["banana"]}]
| put elements = Array.unshift(array, 'pajama', 'potatoes')