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.ar         


        

Answer 1

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

Answer 2

With ES2018, you can now write options = { ...defaults, ...options }:

Spread syntax - JavaScript | MDN

Shallow-cloning (excluding prototype) or merging of objects is now possible using a shorter syntax than Object.assign().

const obj1 = { foo: 'bar', x: 42 };
const obj2 = { foo: 'baz', y: 13 };

const clonedObj = { ...obj1 };
// Object { foo: "bar", x: 42 }

const mergedObj = { ...obj1, ...obj2 };
// Object { foo: "baz", x: 42, y: 13 }

Answer 3

try var options = extend(defaults, userOptions);

This way you get all the userOptions and fall back to defaults when they don't pass any options.

Note use any extend implementation you want.

Answer 4

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.