By the time the data has been read within Javascript, it will have the appropriate name. This is just an escape sequence, which doesn't change the value of the data. For example, in a Javascript console:
var x = "foo\/bar";
var y = "foo/bar";
x == y // true
I'm surprised that the forward slashes are being escaped - just "C:/Users/joao/..."
would work fine - but it shouldn't make any difference to the actual value.