String Operators

String manipulation and searching operations.

cat

Concatenate strings together.

Syntax:

{ "cat": [a, b, ...] }

Arguments:

• a, b, … - Values to concatenate (variadic)

Returns: Concatenated string.

Examples:

// Simple concatenation
{ "cat": ["Hello", " ", "World"] }
// Result: "Hello World"

// With variables
{ "cat": ["Hello, ", { "var": "name" }, "!"] }
// Data: { "name": "Alice" }
// Result: "Hello, Alice!"

// Non-strings are converted
{ "cat": ["Value: ", 42] }
// Result: "Value: 42"

{ "cat": ["Is active: ", true] }
// Result: "Is active: true"

// Building paths
{ "cat": ["/users/", { "var": "userId" }, "/profile"] }
// Data: { "userId": 123 }
// Result: "/users/123/profile"

Try it:

substr

Extract a substring.

Syntax:

{ "substr": [string, start] }
{ "substr": [string, start, length] }

Arguments:

• string - Source string
• start - Starting index (0-based, negative counts from end)
• length - Number of characters (optional, negative counts from end)

Returns: Extracted substring.

Examples:

// From start index
{ "substr": ["Hello World", 0, 5] }
// Result: "Hello"

// From middle
{ "substr": ["Hello World", 6] }
// Result: "World"

// Negative start (from end)
{ "substr": ["Hello World", -5] }
// Result: "World"

// Negative length (exclude from end)
{ "substr": ["Hello World", 0, -6] }
// Result: "Hello"

// Get file extension
{ "substr": ["document.pdf", -3] }
// Result: "pdf"

// With variables
{ "substr": [{ "var": "text" }, 0, 10] }
// Data: { "text": "This is a long string" }
// Result: "This is a "

Try it:

in

Check if a value is contained in a string or array.

Syntax:

{ "in": [needle, haystack] }

Arguments:

• needle - Value to search for
• haystack - String or array to search in

Returns: true if found, false otherwise.

Examples:

// String contains substring
{ "in": ["World", "Hello World"] }
// Result: true

{ "in": ["xyz", "Hello World"] }
// Result: false

// Array contains element
{ "in": [2, [1, 2, 3]] }
// Result: true

{ "in": [5, [1, 2, 3]] }
// Result: false

// Check membership
{ "in": [{ "var": "role" }, ["admin", "moderator"]] }
// Data: { "role": "admin" }
// Result: true

// Check substring
{ "in": ["@", { "var": "email" }] }
// Data: { "email": "user@example.com" }
// Result: true

Try it:

length

Get the length of a string or array.

Syntax:

{ "length": value }

Arguments:

• value - String or array

Returns: Length (number of characters or elements).

Examples:

// String length
{ "length": "Hello" }
// Result: 5

// Array length
{ "length": [1, 2, 3, 4, 5] }
// Result: 5

// Empty values
{ "length": "" }
// Result: 0

{ "length": [] }
// Result: 0

// With variables
{ "length": { "var": "items" } }
// Data: { "items": ["a", "b", "c"] }
// Result: 3

// Check minimum length
{ ">=": [{ "length": { "var": "password" } }, 8] }
// Data: { "password": "secret123" }
// Result: true

Try it:

starts_with

Check if a string starts with a prefix.

Syntax:

{ "starts_with": [string, prefix] }

Arguments:

• string - String to check
• prefix - Prefix to look for

Returns: true if string starts with prefix, false otherwise.

Examples:

{ "starts_with": ["Hello World", "Hello"] }
// Result: true

{ "starts_with": ["Hello World", "World"] }
// Result: false

// Check URL scheme
{ "starts_with": [{ "var": "url" }, "https://"] }
// Data: { "url": "https://example.com" }
// Result: true

// Case sensitive
{ "starts_with": ["Hello", "hello"] }
// Result: false

Try it:

ends_with

Check if a string ends with a suffix.

Syntax:

{ "ends_with": [string, suffix] }

Arguments:

• string - String to check
• suffix - Suffix to look for

Returns: true if string ends with suffix, false otherwise.

Examples:

{ "ends_with": ["Hello World", "World"] }
// Result: true

{ "ends_with": ["Hello World", "Hello"] }
// Result: false

// Check file extension
{ "ends_with": [{ "var": "filename" }, ".pdf"] }
// Data: { "filename": "report.pdf" }
// Result: true

// Case sensitive
{ "ends_with": ["test.PDF", ".pdf"] }
// Result: false

Try it:

upper

Convert string to uppercase.

Syntax:

{ "upper": string }

Arguments:

• string - String to convert

Returns: Uppercase string.

Examples:

{ "upper": "hello" }
// Result: "HELLO"

{ "upper": "Hello World" }
// Result: "HELLO WORLD"

// With variable
{ "upper": { "var": "name" } }
// Data: { "name": "alice" }
// Result: "ALICE"

Try it:

lower

Convert string to lowercase.

Syntax:

{ "lower": string }

Arguments:

• string - String to convert

Returns: Lowercase string.

Examples:

{ "lower": "HELLO" }
// Result: "hello"

{ "lower": "Hello World" }
// Result: "hello world"

// Case-insensitive comparison
{ "==": [
    { "lower": { "var": "input" } },
    "yes"
]}
// Data: { "input": "YES" }
// Result: true

Try it:

trim

Remove leading and trailing whitespace.

Syntax:

{ "trim": string }

Arguments:

• string - String to trim

Returns: String with whitespace removed from both ends.

Examples:

{ "trim": "  hello  " }
// Result: "hello"

{ "trim": "\n\ttext\n\t" }
// Result: "text"

// Clean user input
{ "trim": { "var": "userInput" } }
// Data: { "userInput": "  search query  " }
// Result: "search query"

Try it:

split

Split a string into an array.

Syntax:

{ "split": [string, delimiter] }

Arguments:

• string - String to split
• delimiter - Delimiter to split on

Returns: Array of substrings.

Examples:

// Split by space
{ "split": ["Hello World", " "] }
// Result: ["Hello", "World"]

// Split by comma
{ "split": ["a,b,c", ","] }
// Result: ["a", "b", "c"]

// Split by empty string (characters)
{ "split": ["abc", ""] }
// Result: ["a", "b", "c"]

// Parse CSV-like data
{ "split": [{ "var": "tags" }, ","] }
// Data: { "tags": "rust,json,logic" }
// Result: ["rust", "json", "logic"]

// Get first part
{ "var": "0" }
// Applied to: { "split": ["user@example.com", "@"] }
// Result: "user"

Try it: