What Means Two Keys in Javascript

Question

I understood the "===" that tests value and type, different from the "==" that tests only value, but I didn’t understand the double key, type: {{alguma_coisa}}, for example in a Javascript that I have, have something like this:

mozL10n.get('page_of', {pageCount: pagesCount}, 'de {{pageCount}}');

There is even the need for two keys?

Answer 1

This is specific to this Non-standard API. Avoid using it.

Is a placeholder. It is used to produce an interpolation of string, although it uses a simpler form. It is very similar to the {0} used in C#, but a little better because the expression can be used inside the string, as in the interpolation of string of the C#. This expression will be evaluated and the result will be printed at this location.

The double keys were chosen to avoid any ambiguity, it could be anything else. The important thing is to have some character that marks the beginning and end of the expression and that is something little used in normal texts, to avoid having to escape and print this normally.

Answer 2

In this example:

var a = {};
console.log(a);

It is only used to initialize an object with no value in it.

In his Example:

mozL10n.get('page_of', {pageCount: pagesCount}, 'de {{pageCount}}');

It is used as a standard template for identification of values that will be modified, this is not javascript, but a convention of your API.