defaults(target, [ ... sources])

Mimics _.defaults. Assigns first level properties in sources from left to right if they are not already defined.

var defaults = require("can-util/js/defaults/defaults");

var obj = {a: 1, b: 2};
var src = {b: 3, c: 3};

assign(obj, src, {a: 2, d: 4});

console.log(obj); // -> {a: 1, b: 2, c: 3, d: 4}