JavaScript Enlightenment

Chapter 10. String()

Conceptual Overview of Using the String() Object

The String() constructor function is used to create string objects and string primitive values.

In the code below, I detail the creation of string values in JavaScript.

Live Code

<!DOCTYPE html><html lang="en"><body><script>

// create string object using the new keyword and the String() constructor
var stringObject = new String('foo');
console.log(stringObject); // logs foo {0 = 'f', 1 = 'o', 2 = 'o'}
console.log(typeof stringObject); // logs 'object'

// create string literal/primitive by directly using the String constructor
var stringObjectWithOutNewKeyword = String('foo'); // without new keyword
console.log(stringObjectWithOutNewKeyword); // logs 'foo'
console.log(typeof stringObjectWithOutNewKeyword); // logs 'string'

// create string literal/primitive (constructor leveraged behind the scene)
var stringLiteral = 'foo';
console.log(stringLiteral); // logs foo
console.log(typeof stringLiteral); // logs 'string'
</script></body></html>

String() Parameters

The String() constructor function takes one parameter: the string value being created. Below, we create a variable, stringObject, to contain the string value 'foo'.

Live Code

<!DOCTYPE html><html lang="en"><body><script>


// create string object
var stringObject = new String('foo');

console.log(stringObject); // logs 'foo {0="f", 1="o", 2="o"}'

</script></body></html>

Note

Instances from the String() constructor, when used with the new keyword, produce an actual complex ...