Javascript AMD pattern confusion - persisting property values

问题

So I am trying to get my head around the javascript AMD pattern using requireJS. My experience with JS is limited and no doubt this is what is hampering me. I would not be surprised if I am pointed in the direction of "JS for Dummies". If anyone can bear to help me with this I would be VERY grateful.

I have defined a module called "security" which has the following definition - cut down a bit.

define(['services/storage'], function(storage) {

var security = {
    authToken: {},
    loadAuthToken: loadAuthToken,
    saveAuthToken: saveAuthToken,
};

return security;

function saveAuthToken(token) {
    if (token) {
        storage.save("DiffusrAuthToken", token);
        security.authToken = token;
    }     
};

function loadAuthToken() {       
    if (security.authToken.expires) {
        return security.authToken;
    } else {
        var token = storage.load("DiffusrAuthToken");
        security.authToken = token;
        return token;
    }
};
})

Essentially I want to save the state of some values defined in the module, in the case above, the authToken. This is so that when other modules require this module I don't have to go to localStorage to get it. The only way I can get this to work is by defining a property of the return object, and setting this to an empty object initially. This does not seem satifactory, because I do not want to expose it directly to other modules as they could change it.

The non-AMD way would be to define an object in the global scope and attach properties to it. BUT, I thought the whole point of AMD was to avoid this.

Question: How, generally, should I set values in modules that can be accessed from other modules?

回答1:

Anything you don't export in a module cannot be accessed outside the module but is still available within the module closure. For example, you can create a var but never attach it as a property of the security export object. You can create specific accessor methods to the export object that can access this private variable only in a way that you want users of the module to, as you have done with your saveAuthToken and loadAuthToken methods.

define(['services/storage'], function(storage) {

var authToken;  // private to security module

function saveAuthToken(token) {
    if (token) {
        storage.save("DiffusrAuthToken", token);
        authToken = token;  // store to private variable
    }     
};

function loadAuthToken() {       
    if (authToken.expires) {
        return authToken;
    } else {
        var token = storage.load("DiffusrAuthToken");
        authToken = token;
        return token;
    }
};

// export contains no reference to authToken
var security = {
    loadAuthToken: loadAuthToken,
    saveAuthToken: saveAuthToken,
};

return security;

});

来源：https://stackoverflow.com/questions/20058286/javascript-amd-pattern-confusion-persisting-property-values

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javascript

requirejs