+!! operator in an if statement

Question

I was reviewing the code for an angularjs factory to better understand how it works. The code contains an if statement that I don\'t fully understand.

I

Answer 1

if ((+!!config.template) + (+!!config.templateUrl) !== 1) {

            0            +         0               !== 1  true
            0            +         1               !== 1  false
            1            +         0               !== 1  false
            1            +         1               !== 1  true

is equal to

if (!config.template === !config.templateUrl) {

despite the content of the two properties.