How to get value from Object, with default value

Question

I constantly find myself passing config values to functions accessing them like this:

var arg1 = 'test1'; if(isUndefined(config.args.arg1)){   arg1 = config.args.arg1; }   var arg2 = 'param2'; if(isUndefined(config.args.arg2)){   arg2 = config.args.arg2; }   var arg3 = '123'; if(isUndefined(config.args.arg3)){   arg3 = config.args.arg3; }  

where I later use them like this:

var url = '<some-url>?id='+arg1+'&='+arg2 +'=' + arg3; 

Does jQuery/ExtJS or any other framework provide a solution to access variables like this in a simple way, and give variables a default value?

Something like:

getValueOfObject(config,'args.arg3','<default>'); 

Or is there maybe a standard solution for this.

NOTE:

I was also thinking about the common pattern where you have defaults

var defaults = {    args: {       args1: ....    }    ... } 

and doing an object merge.

And then encoding the object to a param String. But as you can see the object values also sometimes contain parameter names.

Answer 1

Generally, one can use the or operator to assign a default when some variable evaluates to falsy:

var foo = couldBeUndefined || "some default"; 

so:

var arg1 = config.args.arg1 || "test"; var arg2 = config.args.arg2 || "param2"; 

assuming that config.args is always defined, as your example code implies.

Answer 2

Looks like finally lodash has the _.get() function for this!