Why, in JavaScript, does ‘3 instanceof Number’ == false, but ‘3..method()’ will call Number.prototype.method?

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The literal is not coerced into an instance.

What happens internally, is that an instance is created, the value is copied to the instance and the method is carried out using the instance. Then the instance is destroyed. The literal is not actually being used to carry out the method. This “wrapper” object concept is also used with string primitives when they are used like String objects. This behavior is standard.

3 is a number literal. Not an instance of the Number type. JavaScript has a primitive number type and a native Number object.

From MDN: In contexts where a method is to be invoked on a
primitive string or a property lookup occurs, JavaScript will
automatically wrap the string primitive and call the method or perform
the property lookup.

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