Theconcat() method ofString values concatenatesthe string arguments to this string and returns a new string.

Try it

const str1 = "Hello";const str2 = "World";console.log(str1.concat(" ", str2));// Expected output: "Hello World"console.log(str2.concat(", ", str1));// Expected output: "World, Hello"

Syntax

concat(str1)concat(str1, str2)concat(str1, str2, /* …, */ strN)

Parameters

str1, …,strN

One or more strings to concatenate tostr. Though technically permitted, callingString.prototype.concat() with no arguments is a useless operation, because it does not result in observable copying (likeArray.prototype.concat()), since strings are immutable. It should only happen if you arespreading an array of strings as arguments, and that array happens to be empty.

Return value

A new string containing the combined text of the strings provided.

Description

Theconcat() function concatenates the string arguments to the calling string and returns a new string.

If the arguments are not of the type string, they are converted to string values beforeconcatenating.

Theconcat() method is very similar to theaddition/string concatenation operators (+,+=), except thatconcat()coerces its arguments directly to strings, while addition coerces its operands to primitives first. For more information, see the reference page for the+ operator.

Examples

Using concat()

The following example combines strings into a new string.

const hello = "Hello, ";console.log(hello.concat("Kevin", ". Have a nice day."));// Hello, Kevin. Have a nice day.const greetList = ["Hello", " ", "Venkat", "!"];"".concat(...greetList); // "Hello Venkat!""".concat({}); // "[object Object]""".concat([]); // """".concat(null); // "null""".concat(true); // "true""".concat(4, 5); // "45"

Specifications

Browser compatibility

See also

• Array.prototype.concat()
• Addition (+)