Recursion not fully traversing object with nested objects

Question

I'm intending to write a module that can be instantiated with default configuration and then overridden with custom configuration when initialized. The configuration object has nested objects, so I need to traverse over these nested objects if they are included in the custom configuration. I am attempting to do so by calling customize recursively. This works for the first nested object but the traversal ends after that object. Why is this and what can I do to fully traverse an object containing nested objects?

function Config(options) {

    function customize(conf) {
        if (conf && conf.constructor === Object) {
            for (var prop in conf) {         
                if(conf[prop].constructor === Object) {
                    return customize.call(this[prop], conf[prop]);
                } else {
                    if (this.hasOwnProperty(prop)){
                        this[prop] = conf[prop];
                    }
                }
            }
        } else {
            console.error('The first argument must be an object.');
            return;                
        }
    }

    //Default config values
    this.foo = 'default';
    this.bar = {
        foo: 'default'    
    };
    this.baz = {
        foo: 'default'
    };

    //Overide default config with custom config
    if (options && options.constructor === Object) {
        customize.call(this, options);
    }
}  

function TestModule(){        
    this.init = function(options){
        this.config = (options && options.constructor === Object) ? new Config(options) : new Config();
        return this;
    };
}

console.log(
    new TestModule().init({
        foo: 'custom',
        bar: {foo: 'custom'},
        baz: {foo: 'custom'}
    }).config
);

//RESULT
// {
//     foo: 'custom',
//     bar: {foo: 'custom'},
//     baz: {foo: 'default'}
// }

Mike Atkins · Accepted Answer · 2015-02-22 01:46:54Z

2

This line:

return customize.call(this[prop], conf[prop]);

occurs inside a for loop, so you are returning before each item has been iterated over. Your return statement should be outside the loop.

answered Feb 22, 2015 at 1:46

Mike Atkins

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1 Comment

maxhallinan Over a year ago

This works. I was under the impression that recursive calls were always made as part of a return statement. But obviously, doing so ends the loop.

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