String() constructor

The String() constructor creates {{jsxref("String")}}  objects. When called as a function, it returns primitive values of type String.

Syntax

new String(thing)
String(thing)

[!NOTE] String() can be called with or without new, but with different effects. See Return value.

Parameters

• thing
  • : Anything to be converted to a string.

Return value

When String() is called as a function (without new), it returns value coerced to a string primitive. Specially, Symbol values are converted to "Symbol(description)", where description is the description of the Symbol, instead of throwing.

When String() is called as a constructor (with new), it coerces value to a string primitive (without special symbol handling) and returns a wrapping {{jsxref("String")}}  object, which is not a primitive.

[!WARNING] You should rarely find yourself using String as a constructor.

Examples

String constructor and String function

String function and String constructor produce different results:

const a = new String("Hello world"); // a === "Hello world" is false
const b = String("Hello world"); // b === "Hello world" is true
a instanceof String; // is true
b instanceof String; // is false
typeof a; // "object"
typeof b; // "string"

Here, the function produces a string (the {{Glossary("primitive")}}  type) as promised. However, the constructor produces an instance of the type String (an object wrapper) and that’s why you rarely want to use the String constructor at all.

Using String() to stringify a symbol

String() is the only case where a symbol can be converted to a string without throwing, because it’s very explicit.

const sym = Symbol("example");
`${sym}`; // TypeError: Cannot convert a Symbol value to a string
"" + sym; // TypeError: Cannot convert a Symbol value to a string
"".concat(sym); // TypeError: Cannot convert a Symbol value to a string

const sym = Symbol("example");
String(sym); // "Symbol(example)"

Specifications

{{Specifications}} 

Browser compatibility

{{Compat}} 

See also

• Numbers and strings guide