@rbxts/jsnatives

concat

Combines multiple strings into a single string.

Signature

function concat(...args: PatternAdmissible[]): string

Description

The concat function combines zero or more strings into a new string. It accepts any number of arguments which can be strings, numbers, or booleans (which will be converted to strings).

Parameters

...args: A list of values to join together. Each value can be a string, number, or boolean.

Return value

A new string containing all the concatenated values.
If no arguments are provided, an empty string is returned.

Examples

Basic usage

// Concatenate strings
const result = String.concat("Hello", " ", "world");
print(result); // Outputs: "Hello world"

// Concatenate with no arguments
const empty = String.concat();
print(empty); // Outputs: "" (empty string)

Using non-string values

// Numbers and booleans are converted to strings
const withNumber = String.concat("The answer is ", 42);
print(withNumber); // Outputs: "The answer is 42"

const withBoolean = String.concat("Is it true? ", true);
print(withBoolean); // Outputs: "Is it true? true"

// Mix different types
const mixed = String.concat("Value: ", 42, ", Enabled: ", true);
print(mixed); // Outputs: "Value: 42, Enabled: true"

Concatenating arrays of strings

// Using spread operator with arrays
const parts = ["Hello", " ", "world"];
const joined = String.concat(...parts);
print(joined); // Outputs: "Hello world"

// Concatenate with array and additional values
const prefix = "Welcome: ";
const name = ["John", " ", "Doe"];
const message = String.concat(prefix, ...name);
print(message); // Outputs: "Welcome: John Doe"

Practical applications

// Build an address string
function formatAddress(street: string, city: string, state: string, zip: string): string {
  return String.concat(street, ", ", city, ", ", state, " ", zip);
}

const address = formatAddress("123 Main St", "Anytown", "CA", "12345");
print(address); // Outputs: "123 Main St, Anytown, CA 12345"

// Create URL with query parameters
function buildUrl(baseUrl: string, params: Record<string, any>): string {
  let url = baseUrl;
  let isFirst = true;

  for (const [key, value] of Object.entries(params)) {
    const separator = isFirst ? "?" : "&";
    url = String.concat(url, separator, key, "=", value);
    isFirst = false;
  }

  return url;
}

const url = buildUrl("https://example.com", { user: "john", id: 42 });
print(url); // Outputs: "https://example.com?user=john&id=42"

Comparison with string addition

// Using concat
const withConcat = String.concat("Hello", " ", "world");

// Using string addition (with + operator)
const withAddition = "Hello" + " " + "world";

print(withConcat === withAddition); // Outputs: true