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Bootstrap Function Declaration

I was taking a look through the bootstrap JS source and I came across something that I haven't seen before:

+function ($) { "use strict";
//...
}(window.jQuery);

What's the deal with the + in front of the function declaration? Is it to mitigate some potential minification problems or something?

I believe that placing a + before an expression type converts the result of the expression to a number, but I don't see what the relevance of that would be here.

Thanks for anybody who can shed some light on this for me.

Solution

  • That is so that the function declaration is a function expression, so that it can be executed immediately.

    Usually that is done by putting parentheses around it:

    (function ($) { "use strict";
//...
}(window.jQuery));

    or:

    (function ($) { "use strict";
//...
})(window.jQuery);