This is the fifth post in a series I'm writing as I learn JavaScript.

By now this series has a running theme: I learn a rule, then I find something that seems to break it, and chasing down why teaches me more than the rule did.

Here's this one.

I'd just learned that strings are primitives . Not objects — primitives. A string is a single value, like a number or a boolean. Fine.

Then, on the same day, I wrote this:

let name = " parth " ; console . log ( name . toUpperCase ()); // "PARTH" console . log ( name . length ); // 5

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And stopped.

.toUpperCase() is a method . .length is a property . Those belong to objects . But I was just told a string is a primitive, not an object. So how does a primitive have methods hanging off it?

Either strings are secretly objects, or something sneaky is happening. It turns out to be the second one, and it has a name: autoboxing .

First, strings really are primitives

Just to be sure I hadn't misunderstood:

console .…