Js.String
Provide bindings to JS string
JavaScript String API
let make: 'a => t;
make value
converts the given value to a string
make 3.5 = "3.5";;
make [|1;2;3|]) = "1,2,3";;
let fromCharCode: int => t;
fromCharCode n
creates a string containing the character corresponding to that number; n ranges from 0 to 65535. If out of range, the lower 16 bits of the value are used. Thus, fromCharCode 0x1F63A
gives the same result as fromCharCode 0xF63A
.
fromCharCode 65 = "A";;
fromCharCode 0x3c8 = {js|ψ|js};;
fromCharCode 0xd55c = {js|한|js};;
fromCharCode -64568 = {js|ψ|js};;
let fromCharCodeMany: array(int) => t;
fromCharCodeMany [|n1;n2;n3|]
creates a string from the characters corresponding to the given numbers, using the same rules as fromCharCode
.
fromCharCodeMany([|0xd55c, 0xae00, 33|]) = {js|한글!|js};;
let fromCodePoint: int => t;
fromCodePoint n
creates a string containing the character corresponding to that numeric code point. If the number is not a valid code point, raises RangeError
. Thus, fromCodePoint 0x1F63A
will produce a correct value, unlike fromCharCode 0x1F63A
, and fromCodePoint -5
will raise a RangeError
.
fromCodePoint 65 = "A";;
fromCodePoint 0x3c8 = {js|ψ|js};;
fromCodePoint 0xd55c = {js|한|js};;
fromCodePoint 0x1f63a = {js|😺|js};;
let fromCodePointMany: array(int) => t;
fromCharCodeMany [|n1;n2;n3|]
creates a string from the characters corresponding to the given code point numbers, using the same rules as fromCodePoint
.
fromCodePointMany([|0xd55c; 0xae00; 0x1f63a|]) = {js|한글😺|js}
let length: t => int;
length s
returns the length of the given string.
length "abcd" = 4;;
get s n
returns as a string the character at the given index number. If n
is out of range, this function returns undefined
, so at some point this function may be modified to return t option
.
get "Reason" 0 = "R";;
get "Reason" 4 = "o";;
get {js|Rẽasöń|js} 5 = {js|ń|js};;
charAt ~index s
gets the character at position index
within string s
. If index
is negative or greater than the length of s
, returns the empty string. If the string contains characters outside the range \u0000-\uffff
, it will return the first 16-bit value at that position in the string.
charAt ~index:0 "Reason" = "R"
charAt ~index:12 "Reason" = "";
charAt ~index:5 {js|Rẽasöń|js} = {js|ń|js}
let charCodeAt: index:int => t => float;
charCodeAt s ~index
returns the character code at position index
in string s
; the result is in the range 0-65535, unlke codePointAt
, so it will not work correctly for characters with code points greater than or equal to 0x10000
. The return type is float
because this function returns NaN
if index
is less than zero or greater than the length of the string.
charCodeAt ~index:0 {js|😺|js} = 0xd83d
codePointAt ~index:0 {js|😺|js} = Some 0x1f63a
let codePointAt: index:int => t => option(int);
codePointAt s ~index
returns the code point at position index
within string s
as a Some
value. The return value handles code points greater than or equal to 0x10000
. If there is no code point at the given position, the function returns None
.
codePointAt ~index:1 {js|¿😺?|js} = Some 0x1f63a
codePointAt ~index:5 "abc" = None
ES2015
concat ~other:str2 str1
returns a new string with str2
added after str1
.
concat ~other:"bell" "cow" = "cowbell";;
concatMany ~strings original
returns a new string consisting of each item of the array of strings strings
added to the original
string.
concatMany ~strings:[|"2nd"; "3rd"; "4th"|] "1st" = "1st2nd3rd4th";;
endsWith ~suffix ?len str
returns true
if the str
ends with suffix
, false
otherwise. If len
is specified, `endsWith` only takes into account the first len
characters.
endsWith ~suffix:"cd" ~len:4 "abcd" = true;;
endsWith ~suffix:"cd" ~len:3 "abcde" = false;;
endsWith ~suffix:"cde" ~len:99 "abcde" = true;;
endsWith ~suffix:"ple" ~len:7 "example.dat" = true;;
endsWith ~suffix:"World!" "Hello, World!" = true;;
endsWith ~suffix:"world!" "Hello, World!" = false;; (* case-sensitive *)
endsWith ~suffix:"World" "Hello, World!" = false;; (* exact match *)
includes ~search ?start s
returns true
if search
is found anywhere within s
starting at character number start
(where 0 is the first character), false
otherwise.
includes ~search:"gram" "programmer" = true;;
includes ~search:"er" "programmer" = true;;
includes ~search:"pro" "programmer" = true;;
includes ~search:"xyz" "programmer" = false;;
includes ~search:"gram" ~start:1 "programmer" = true;;
includes ~search:"gram" ~start:4 "programmer" = false;;
includes ~search:{js|한|js} ~start:1 {js|대한민국|js} = true;;
indexOf ~search ?start s
returns the position at which search
was found within s
starting at character position start
, or -1
if search
is not found in that portion of s
. The return value is relative to the beginning of the string, no matter where the search started from.
indexOf ~search:"ok" "bookseller" = 2;;
indexOf ~search:"sell" "bookseller" = 4;;
indexOf ~search:"ee" "beekeeper" = 1;;
indexOf ~search:"xyz" "bookseller" = -1;;
indexOf ~search:"ok" ~start:1 "bookseller" = 2;;
indexOf ~search:"sell" ~start:2 "bookseller" = 4;;
indexOf ~search:"sell" ~start:5 "bookseller" = -1;;
lastIndexOf ~search ~start s
returns the position of the last occurrence of searchValue
within s
, searching backwards from the given start
position. Returns -1
if searchValue
is not in s
. The return value is always relative to the beginning of the string.
lastIndexOf ~search:"ok" "bookseller" = 2;;
lastIndexOf ~search:"ee" "beekeeper" = 4;;
lastIndexOf ~search:"xyz" "abcdefg" = -1;;
lastIndexOf ~search:"ok" ~start:6 "bookseller" = 2;;
lastIndexOf ~search:"ee" ~start:8 "beekeeper" = 4;;
lastIndexOf ~search:"ee" ~start:3 "beekeeper" = 1;;
lastIndexOf ~search:"xyz" ~start:4 "abcdefg" = -1;;
localeCompare ~other:comparison reference
returns:
reference
comes before comparison
in sort orderreference
and comparison
have the same sort orderreference
comes after comparison
in sort order(localeCompare ~other:"ant" "zebra") > 0.0;;
(localeCompare ~other:"zebra" "ant") < 0.0;;
(localeCompare ~other:"cat" "cat") = 0.0;;
(localeCompare ~other:"cat" "CAT") > 0.0;;
match ~regexp str
matches a string against the given regexp
. If there is no match, it returns None
. For regular expressions without the g
modifier, if there is a match, the return value is Some array
where the array contains:
regexp
had parenthesesFor regular expressions with the g
modifier, a matched expression returns Some array
with all the matched substrings and no capture groups.
match "The better bats" ~regexp:[%re "/b[aeiou]t/"] = Some [|"bet"|]
match "The better bats" ~regexp:[%re "/b[aeiou]t/g"] = Some [|"bet";"bat"|]
match "Today is 2018-04-05." ~regexp:[%re "/(\\d+)-(\\d+)-(\\d+)/"] = Some [|"2018-04-05"; "2018"; "04"; "05"|]
match "The large container." ~regexp:[%re "/b[aeiou]g/"] = None
normalize ~form str
returns the normalized Unicode string using the specified form of normalization, which may be one of:
`NFC
— Normalization Form Canonical Composition.`NFD
— Normalization Form Canonical Decomposition.`NFKC
— Normalization Form Compatibility Composition.`NFKD
— Normalization Form Compatibility Decomposition.If form
is omitted, `NFC
is used.
Consider the character ã
, which can be represented as the single codepoint \u00e3
or the combination of a lower case letter A \u0061
and a combining tilde \u0303
. Normalization ensures that both can be stored in an equivalent binary representation.
repeat ~count s
returns a string that consists of count
repetitions of s
. Raises RangeError
if n
is negative.
repeat ~count:3 "ha" = "hahaha"
repeat ~count:0 "empty" = ""
replace ~search ~replacement string
returns a new string which is identical to string
except with the first matching instance of search
replaced by replacement
.
search
is treated as a verbatim string to match, not a regular expression.
replace ~search:"old" ~replacement:"new" "old string" = "new string"
replace ~search:"the" ~replacement:"this" "the cat and the dog" = "this cat and the dog"
replaceByRe ~regexp ~replacement string
returns a new string where occurrences matching regexp
have been replaced by replacement
.
replaceByRe ~regexp:[%re "/[aeiou]/g"] ~replacement:"x" "vowels be gone" = "vxwxls bx gxnx"
replaceByRe ~regexp:[%re "/(\\w+) (\\w+)/"] ~replacement:"$2, $1" "Juan Fulano" = "Fulano, Juan"
unsafeReplaceBy0 ~regexp ~f s
returns a new string with some or all matches of a pattern with no capturing parentheses replaced by the value returned from the given function. The function receives as its parameters the matched string, the offset at which the match begins, and the whole string being matched
let str = "beautiful vowels"
let re = [%re "/[aeiou]/g"]
let matchFn matchPart offset wholeString = Js.String.toUpperCase matchPart
let replaced = Js.String.unsafeReplaceBy0 ~regexp:re ~f:matchFn str
let () = Js.log replaced (* prints "bEAUtifUl vOwEls" *)
@see <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace#Specifying_a_function_as_a_parameter> MDN
unsafeReplaceBy1 ~regexp ~f s
returns a new string with some or all matches of a pattern with one set of capturing parentheses replaced by the value returned from the given function. The function receives as its parameters the matched string, the captured strings, the offset at which the match begins, and the whole string being matched.
let str = "increment 23"
let re = [%re "/increment (\\d+)/g"]
let matchFn matchPart p1 offset wholeString =
wholeString ^ " is " ^ (string_of_int ((int_of_string p1) + 1))
let replaced = Js.String.unsafeReplaceBy1 ~regexp:re ~f:matchFn str
let () = Js.log replaced (* prints "increment 23 is 24" *)
@see <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace#Specifying_a_function_as_a_parameter> MDN
unsafeReplaceBy2 ~regexp ~f s
returns a new string with some or all matches of a pattern with two sets of capturing parentheses replaced by the value returned from the given function. The function receives as its parameters the matched string, the captured strings, the offset at which the match begins, and the whole string being matched.
let str = "7 times 6"
let re = [%re "/(\\d+) times (\\d+)/"]
let matchFn matchPart p1 p2 offset wholeString =
string_of_int ((int_of_string p1) * (int_of_string p2))
let replaced = Js.String.unsafeReplaceBy2 ~regexp:re ~f:matchFn str
let () = Js.log replaced (* prints "42" *)
unsafeReplaceBy3 ~regexp ~f s
returns a new string with some or all matches of a pattern with three sets of capturing parentheses replaced by the value returned from the given function. The function receives as its parameters the matched string, the captured strings, the offset at which the match begins, and the whole string being matched.
let search: regexp:Js__.Js_re.t => t => int;
search ~regexp str
returns the starting position of the first match of regexp
in the given str
, or -1 if there is no match.
search ~regexp:[%re "/\\d+/"] "testing 1 2 3" = 8;;
search ~regexp:[%re "/\\d+/"] "no numbers" = -1;;
slice ?start ?end str
returns the substring of str
starting at character start
up to but not including end
If either start
or end
is negative, then it is evaluated as length str
- start
(or length str - end
).
If end
is greater than the length of str
, then it is treated as length
str
.
If start
is greater than end
, slice
returns the empty string.
slice ~start:2 ~end_:5 "abcdefg" = "cde";;
slice ~start:2 ~end_:9 "abcdefg" = "cdefg";;
slice ~start:(-4) ~end_:(-2) "abcdefg" = "de";;
slice ~start:5 ~end_:1 "abcdefg" = "";;
split ?sep ?limit str
splits the given str
at every occurrence of sep
and returns an array of the first limit
resulting substrings. If limit
is negative or greater than the number of substrings, the array will contain all the substrings.
split ~sep:"/" ~limit: 3 "ant/bee/cat/dog/elk" = [|"ant"; "bee"; "cat"|];;
split ~sep:"/" ~limit: 0 "ant/bee/cat/dog/elk" = [| |];;
split ~sep:"/" ~limit: 9 "ant/bee/cat/dog/elk" = [|"ant"; "bee"; "cat"; "dog"; "elk"|];;
splitByRe str ~regexp ?limit ()
splits the given str
at every occurrence of regexp
and returns an array of the first limit
resulting substrings. If limit
is negative or greater than the number of substrings, the array will contain all the substrings.
splitByRe ~regexp:[%re "/\\s*:\\s*/"] ~limit:3 "one: two: three: four" = [|"one"; "two"; "three"|];;
splitByRe ~regexp:[%re "/\\s*:\\s*/"] ~limit:0 "one: two: three: four" = [| |];;
splitByRe ~regexp:[%re "/\\s*:\\s*/"] ~limit:8 "one: two: three: four" = [|"one"; "two"; "three"; "four"|];;
;
startsWith ~prefix ?start str
returns true
if the str
starts with prefix
starting at position start
, false
otherwise. If start
is negative, the search starts at the beginning of str
.
startsWith ~prefix:"Hello" ~start:0 "Hello, World!" = true;;
startsWith ~prefix:"World" ~start:7 "Hello, World!" = true;;
startsWith ~prefix:"World" ~start:8 "Hello, World!" = false;;
substr ?start ?len str
returns the substring of str
of length len
starting at position start
.
If start
is less than zero, the starting position is the length of str
start
.If start
is greater than or equal to the length of str
, returns the empty string.
If len
is less than or equal to zero, returns the empty string.
substr ~start:3 ~len:4 "abcdefghij" = "defghij"
substr ~start:(-3) ~len:4 "abcdefghij" = "hij"
substr ~start:12 ~len:2 "abcdefghij" = ""
substring ~start ~end_ str
returns characters start
up to but not including end_
from str
.
If start
is less than zero, it is treated as zero.
If end_
is zero or negative, the empty string is returned.
If start
is greater than end_
, the start and finish points are swapped.
substring ~start:3 ~end_:6 "playground" = "ygr";;
substring ~start:6 ~end_:3 "playground" = "ygr";;
substring ~start:4 ~end_:12 "playground" = "ground";;
toLowerCase str
converts str
to lower case using the locale-insensitive case mappings in the Unicode Character Database. Notice that the conversion can give different results depending upon context, for example with the Greek letter sigma, which has two different lower case forms when it is the last character in a string or not.
toLowerCase "ABC" = "abc";;
toLowerCase {js|ΣΠ|js} = {js|σπ|js};;
toLowerCase {js|ΠΣ|js} = {js|πς|js};;
toLocaleLowerCase str
converts str
to lower case using the current locale
toUpperCase str
converts str
to upper case using the locale-insensitive case mappings in the Unicode Character Database. Notice that the conversion can expand the number of letters in the result; for example the German ß
capitalizes to two S
es in a row.
toUpperCase "abc" = "ABC";;
toUpperCase {js|Straße|js} = {js|STRASSE|js};;
toUpperCase {js|πς|js} = {js|ΠΣ|js};;
toLocaleUpperCase str
converts str
to upper case using the current locale
trim str
returns a string that is str
with whitespace stripped from both ends. Internal whitespace is not removed.
trim " abc def " = "abc def"
trim "\n\r\t abc def \n\n\t\r " = "abc def"
anchor ~name:anchorName anchorText
creates a string with an HTML <a>
element with name
attribute of anchorName
and anchorText
as its content.
anchor ~name:"page1" "Page One" = "<a name=\"page1\">Page One</a>"
link ~href:urlText linkText
creates a string with an HTML <a>
element with href
attribute of urlText
and linkText
as its content.
link ~href:"page2.html" "Go to page two" = "<a href=\"page2.html\">Go to page two</a>"