String functions

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$string

Signature: $string(arg, prettify) Parameters:

• arg - An argument to be cast to string.
• prettify - If prettify is true, then “prettified” JSON is produced. i.e one line per field and lines will be indented based on the field depth.

Casts the arg parameter to a string. If arg is not specified (i.e. this function is invoked with no arguments), then the context value is used as the value of arg. If prettify is true, then “prettified” JSON is produced. i.e one line per field and lines will be indented based on the field depth. Examples

Expression	Result
$string(5)	"5"
[1..5].$string()	["1", "2", "3", "4", "5"]

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$length

Signature: $length(str) Parameters:

• str - A string to get the length of.

An error is thrown if str is not a string. Returns the number of characters in the string str. If str is not specified (i.e. this function is invoked with no arguments), then the context value is used as the value of str. An error is thrown if str is not a string. Examples

Expression	Result
$length("Hello World")	11

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$substring

Signature: $substring(str, start[, length]) Parameters:

• str - The source string.
• start - The index of the first character to include in the returned substring.

If start is negative then it indicates the number of characters from the end of str.

• length - If length is specified, then the substring will contain maximum length characters.

Returns a string containing the characters in the first parameter str starting at position start (zero-offset). If str is not specified (i.e. this function is invoked with only the numeric argument(s)), then the context value is used as the value of str. If length is specified, then the substring will contain maximum length characters. If start is negative then it indicates the number of characters from the end of str. Examples

Expression	Result
$substring("Hello World", 3)	"lo World"
$substring("Hello World", 3, 5)	"lo Wo"
$substring("Hello World", -4)	"orld"
$substring("Hello World", -4, 2)	"or"

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$substringBefore

Signature: $substringBefore(str, chars) Parameters:

• str - The source string.
• chars - A character sequence to search for within the str.

If str does not contain chars, then this function returns str. Returns the substring before the first occurrence of the character sequence chars in str. If str is not specified (i.e. this function is invoked with only one argument), then the context value is used as the value of str. If str does not contain chars, then it returns str. Examples

Expression	Result
$substringBefore("Hello World", " ")	"Hello"

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$substringAfter

Signature: $substringAfter(str, chars) Parameters:

• str - The source string.
• chars - A character sequence to search for within the str.

If str does not contain chars, then this function returns str. Returns the substring after the first occurrence of the character sequence chars in str. If str is not specified (i.e. this function is invoked with only one argument), then the context value is used as the value of str. If str does not contain chars, then it returns str. Examples

Expression	Result
$substringAfter("Hello World", " ")	"World"

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$uppercase

Signature: $uppercase(str) Parameters:

• str - The source string.

Returns a string with all the characters of str converted to uppercase. If str is not specified (i.e. this function is invoked with no arguments), then the context value is used as the value of str Examples

Expression	Result
$uppercase("Hello World")	"HELLO WORLD"

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$lowercase

Signature: $lowercase(str) Parameters:

• str - The source string.

Returns a string with all the characters of str converted to lowercase. If str is not specified (i.e. this function is invoked with no arguments), then the context value is used as the value of str Examples

Expression	Result
$lowercase("Hello World")	"hello world"

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$trim

Signature: $trim(str) Parameters:

• str - The source string.

An error is thrown if str is not a string. Normalizes and trims all whitespace characters in str by applying the following steps:

• All tabs, carriage returns, and line feeds are replaced with spaces.
• Contiguous sequences of spaces are reduced to a single space.
• Trailing and leading spaces are removed.

If str is not specified (i.e. this function is invoked with no arguments), then the context value is used as the value of str. An error is thrown if str is not a string. Examples

Expression	Result
$trim(" Hello \t World")	"Hello World"

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$pad

Signature: $pad(str, width [, char]) Parameters:

• str - The source string.
• width - The desired width of the output.

If width is a positive number, then the str is padded to the right; if negative, it is padded to the left.

• char - The optional char argument specifies the padding character(s) to use.

If not specified, it defaults to the space character. Returns a copy of the string str with extra padding, if necessary, so that its total number of characters is at least the absolute value of the width parameter. If width is a positive number, then the string is padded to the right; if negative, it is padded to the left. The optional char argument specifies the padding character(s) to use. If not specified, it defaults to the space character. Examples

Expression	Result
$pad("foo", 5)	"foo "
$pad("foo", -5)	" foo"
$pad("foo", -5, "#")	"##foo"
$formatBase(35, 2) ~> $pad(-8, '0')	"00100011"

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$contains

Signature: $contains(str, pattern) Parameters:

• str - The source string to search for a pattern in.
• pattern - The pattern parameter can either be a string or a regular expression (regex).

If it is a string, the function returns true if the characters within pattern are contained contiguously within str. If it is a regex, the function will return true if the regex matches the contents of str. Returns true if str is matched by pattern, otherwise it returns false. If str is not specified (i.e. this function is invoked with one argument), then the context value is used as the value of str. The pattern parameter can either be a string or a regular expression (regex). If it is a string, the function returns true if the characters within pattern are contained contiguously within str. If it is a regex, the function will return true if the regex matches the contents of str. Examples

Expression	Result
$contains("abracadabra", "bra")	true
$contains("abracadabra", /a.*a/)	true
$contains("abracadabra", /ar.*a/)	false
$contains("Hello World", /wo/)	false
$contains("Hello World", /wo/i)	true
Phone[$contains(number, /^077/)]	{ "type": "mobile", "number": "077 7700 1234" }

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$split

Signature: $split(str, separator [, limit]) Parameters:

• str - A string to split by the pattern.
• pattern - The separator parameter can either be a string or a regular expression (regex).

If it is a string, it specifies the characters within str about which it should be split. If it is the empty string, str will be split into an array of single characters. If it is a regex, it splits the string around any sequence of characters that match the regex.

• limit - The optional limit parameter is a number that specifies the maximum number of substrings to include in the resultant array. Any additional substrings are discarded.

If limit is not specified, then str is fully split with no limit to the size of the resultant array. It is an error if limit is not a non-negative number. Splits the str parameter into an array of substrings. If str is not specified, then the context value is used as the value of str. It is an error if str is not a string. The separator parameter can either be a string or a regular expression (regex). If it is a string, it specifies the characters within str about which it should be split. If it is the empty string, str will be split into an array of single characters. If it is a regex, it splits the string around any sequence of characters that match the regex. The optional limit parameter is a number that specifies the maximum number of substrings to include in the resultant array. Any additional substrings are discarded. If limit is not specified, then str is fully split with no limit to the size of the resultant array. It is an error if limit is not a non-negative number. Examples

Expression	Result
$split("so many words", " ")	["so", "many", "words"]
$split("so many words", " ", 2)	["so", "many"]
$split("too much, punctuation. hard; to read", /[ ,.;]+/)	["too", "much", "punctuation", "hard", "to", "read"]

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$join

Signature: $join(array[, separator]) Parameters:

• array - An array of strings to join together.

It is an error if the input array contains an item which isn’t a string.

• separator - A string to join the array with.

If separator is not specified, then it is assumed to be the empty string, i.e. no separator between the component strings. It is an error if separator is not a string. Joins an array of component strings into a single concatenated string with each component string separated by the optional separator parameter. It is an error if the input array contains an item which isn’t a string. If separator is not specified, then it is assumed to be the empty string, i.e. no separator between the component strings. It is an error if separator is not a string. Examples

Expression	Result
$join(['a','b','c'])	"abc"
$split("too much, punctuation. hard; to read", /[ ,.;]+/, 3) ~> $join(', ')	"too, much, punctuation"

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$match

Signature: $match(str, pattern [, limit]) Parameters:

• str - A string to match by pattern.
• pattern - A regular expression (regex) used to search for matches within the str.
• limit - The optional limit parameter is a number that specifies the maximum number of matches to include in the resultant array. Any additional matches are discarded.

If limit is not specified, then there’s no limit to the size of the resultant array. It is an error if limit is not a non-negative number. Applies the str string to the pattern regular expression and returns an array of objects, with each object containing information about each occurrence of a match within str. The object contains the following fields:

• match - the substring that was matched by the regex.
• index - the offset (starting at zero) within str of this match.
• groups - if the regex contains capturing groups (parentheses), this contains an array of strings representing each captured group.

If str is not specified, then the context value is used as the value of str. It is an error if str is not a string. Examples

Expression	Result
$match("ababbabbcc",/a(b+)/)	[{ "match": "ab", "index": 0, "groups": ["b"] }, { "match": "abb", "index": 2, "groups": ["bb"] }, { "match": "abb", "index": 5, "groups": ["bb" ] }]

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$replace

Signature: $replace(str, pattern, replacement [, limit]) Parameters:

• str - The source string.
• pattern - The pattern parameter can either be a string or a regular expression (regex).

If it is a string, it specifies the substring(s) within str which should be replaced. If it is a regex, its is used to find.

• replacement - The replacement parameter can either be a string or a function. If it is a string, it specifies the sequence of characters that replace the substring(s) that are matched by pattern. If pattern is a regex, then the replacement string can refer to the characters that were matched by the regex as well as any of the captured groups using a $ followed by a number N:
• If N = 0, then it is replaced by substring matched by the regex as a whole.
• If N > 0, then it is replaced by the substring captured by the Nth parenthesised group in the regex.
• If N is greater than the number of captured groups, then it is replaced by the empty string.
• A literal $ character must be written as $$ in the replacement string

If the replacement parameter is a function, then it is invoked for each match occurrence of the pattern regex. The replacement function must take a single parameter which will be the object structure of a regex match as described in the $match function; and must return a string.

• limit - The optional limit parameter, is a number that specifies the maximum number of replacements to make before stopping. The remainder of the input beyond this limit will be copied to the output unchanged.

Finds occurrences of pattern within str and replaces them with replacement. If str is not specified, then the context value is used as the value of str. It is an error if str is not a string. The pattern parameter can either be a string or a regular expression (regex). If it is a string, it specifies the substring(s) within str which should be replaced. If it is a regex, its is used to find . The replacement parameter can either be a string or a function. If it is a string, it specifies the sequence of characters that replace the substring(s) that are matched by pattern. If pattern is a regex, then the replacement string can refer to the characters that were matched by the regex as well as any of the captured groups using a $ followed by a number N:

• If N = 0, then it is replaced by substring matched by the regex as a whole.
• If N > 0, then it is replaced by the substring captured by the Nth parenthesised group in the regex.
• If N is greater than the number of captured groups, then it is replaced by the empty string.
• A literal $ character must be written as $$ in the replacement string

If the replacement parameter is a function, then it is invoked for each match occurrence of the pattern regex. The replacement function must take a single parameter which will be the object structure of a regex match as described in the $match function; and must return a string. The optional limit parameter, is a number that specifies the maximum number of replacements to make before stopping. The remainder of the input beyond this limit will be copied to the output unchanged. Examples

Expression	Result
$replace("John Smith and John Jones", "John", "Mr")	"Mr Smith and Mr Jones"
$replace("John Smith and John Jones", "John", "Mr", 1)	"Mr Smith and John Jones"
$replace("abracadabra", /a._?a/, "_")	"*c*bra"
$replace("John Smith", /(\w+)\s(\w+)/, "$2, $1")	"Smith, John"
$replace("265USD", /(\[0-9]+)USD/, "$$$1")	"$265"

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$eval

Signature: $eval(str [, context]) Parameters:

• str - A string with literal JSON or a JSONata expression.

Parses and evaluates the string expr which contains literal JSON or a JSONata expression using the current context as the context for evaluation. Examples

Expression	Result
$eval("[1,2,3]")	[1, 2, 3]
$eval('[1,$string(2),3]')	[1,"2",3]

Optionally override the context by specifying the second parameter

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$base64encode

Signature: $base64encode(str) Parameters:

• str - An ASCII string to encode.

Converts an ASCII string to a base 64 representation. Each each character in the string is treated as a byte of binary data. This requires that all characters in the string are in the 0x00 to 0xFF range, which includes all characters in URI encoded strings. Unicode characters outside of that range are not supported. Examples

Expression	Result
$base64encode("myuser:mypass")	"bXl1c2VyOm15cGFzcw=="

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$base64decode

Signature: $base64decode(str) Parameters:

• str - An base64-encoded string to decode.

Converts base 64 encoded bytes to a string, using a UTF-8 Unicode codepage. Examples

Expression	Result
$base64decode("bXl1c2VyOm15cGFzcw==")	"myuser:mypass"

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$encodeUrlComponent

Signature: $encodeUrlComponent(str) Parameters:

• str - An URL component string to encode.

Encodes a Uniform Resource Locator (URL) component by replacing each instance of certain characters by one, two, three, or four escape sequences representing the UTF-8 encoding of the character. Examples

Expression	Result
$encodeUrlComponent("?x=test")	"%3Fx%3Dtest"

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$encodeUrl

Signature: $encodeUrl(str) Parameters:

• str - An URL string to encode.

Encodes a Uniform Resource Locator (URL) by replacing each instance of certain characters by one, two, three, or four escape sequences representing the UTF-8 encoding of the character. Examples

Expression	Result
$encodeUrl("https://mozilla.org/?x=шеллы")	"https://mozilla.org/?x=%D1%88%D0%B5%D0%BB%D0%BB%D1%8B"

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$decodeUrlComponent

Signature: $decodeUrlComponent(str) Parameters:

• str - An encoded URL component string to decode.

Decodes a Uniform Resource Locator (URL) previously created by encodeUrl. Examples

Expression	Result
$decodeUrlComponent("%3Fx%3Dtest")	"?x=test"

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$decodeUrl

Signature: $decodeUrl(str) Parameters:

• str - An encoded URL string to decode.

Decodes a Uniform Resource Locator (URL) previously created by encodeUrl. Examples

Expression	Result
$decodeUrl("https://mozilla.org/?x=%D1%88%D0%B5%D0%BB%D0%BB%D1%8B")	"https://mozilla.org/?x=шеллы"