Object referencing other object about rewire HOT 4 CLOSED

Hi,

unfortunately not, because JavaScript copies primitives like numbers by value. This means, that an assignment creates a copy of the original value. Changing the original value won't change the copy.

For instance:

var a = 2;
var b = a; // assigns the value 2, not the reference a

a = 3;
console.log(b); // 2

Objects (and arrays) on the other hand are copied by reference, so:

var obj1 = {
   foo: "foo"
};
var obj2 = obj1; // assigns the reference of obj1 to obj2

obj1.foo = "bar";
console.log(obj2.foo); // "bar"

from rewire.

Unfortunatly there is no operator to change this behaviour. I think they made this to keep JavaScript simple for beginners. But actually most of the time it's no real problem, it's only annoying if you want to copy an object.

from rewire.

Right, I tried to simplify the example too much making it different from my original use case and thus introduced the passed by value issue without noticing.

This is closer to what I would like to do, maybe this is possible:

var foo = require('./foo');
var bar = require('./bar');

var providers = {
    foo: foo,
    bar: bar
}

module.exports = {
    run: function (provider) {
        return providers[provider];
    }
};

So I have an object providers that has references to two modules. I want to dynamically call one of these modules depending on the params passed into my module.

So in my test I would like to rewire foo and get this line return providers[provider] to return the fake version.

thanks

from rewire.

If you just want to rewire providers.foo you could do:

var subject = rewire('../../services/foo');
subject.__set__("providers.foo", fooMock);

or of course rewire the whole providers-object.

Since the code is executed when calling rewire(), the reference of the original foo-module is copied instantly to the providers-object. So rewiring the foo-module won't change the copied reference. I don't see any other way than manually rewiring every reference in the module.

You could also take a look at injectr. There you can provide mocks for certain require()-calls. 😄

from rewire.