In Javascript, we can call methods on string literals directly without enclosing it within round brackets. But not for other types such as numbers, or functions. It is a syntax error, but is there a reason as to why the Javascript lexer needs these other types to be enclosed in round brackets?

For example, if we extend Number, String, and Function with an alert method and try calling this method on the literals, it's a SyntaxError for Number and Function, while it works for a String.

function alertValue() {
    alert(this);
}

Number.prototype.alert = alertValue;
String.prototype.alert = alertValue;
Function.prototype.alert = alertValue;

We can call alert directly on a string object:

"someStringLiteral".alert() // alerts someStringLiteral

but it's a SyntaxError on numbers, and functions.

7.alert();
function() {}.alert();

To work with these types, we have to enclose it within brackets:

(7).alert(); // alerts "7"
(function() {}).alert(); // alerts "function() {}"