Question

I try to understand this example from jquery api
in this snippet

        var tags = this.map(function () {
        return this.tagName;
    })
            .get().join(", ");

why get() is necessary?
in the api it says that get() Retrieve the DOM elements matched by the jQuery object. In this case, I see that get() is not applied to jq object, but on strings.
When I remove get(), I get this error message:

Uncaught TypeError: Object [object Object] has no method ‘join’

why join can not work with map?

Answer 1

• Here, this is jQuery object with a list of nodes. (All functions in jQuery.fn have their context (i.e.,this) set to the jQuery object that is making the call to the function.)

• The call to map returns a jQuery object with a list of strings. (You may be confusing jQuery’s map function with the map array function introduced in ECMAScript 5,)

• The call to get returns a plain JS array of those strings, and join acts on that array.

The call to get is necessary to transform the jQuery object with a list of strings (returned by map) into a plain JS array so it can be glued together with join.