Question

Can someone explain this JS LINE ? data is an object.

var list = data == null ? [] : (data.wine instanceof Array ? data.wine : [data.wine]);

Answer 1

It is basically this;

var list;

if (data == null) {
    list = [];
} else {
    if (data.wine instanceof Array) {
        list = data.wine;
    } else {
        list = [data.wine];
    }
}

It consists of nested ternary operators. A ternary operator is of the form;

x ? y : z

Which evaluates x, and returns y if it is truthy, otherwise it returns z.